Chapter 5: Death Investigation

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Welcome back to the Deep Dive, the place where we dismantle specialized knowledge and extract the essential, fascinating, and sometimes visceral facts you need to truly be well -informed.

Today we are undertaking a perhaps the most solemn and scientifically demanding deep dive we've done,

death investigation.

Right.

We're drawing from some really comprehensive source material that covers forensic pathology, anthropology, and even entomology to follow the entire process of an investigation.

Okay, let's unpack this.

Our mission is to guide you step by step through that whole journey from the moment an officer secures a scene all the way to the specialized lab analysis that might happen months later.

And we want to understand how experts use chemistry, biology, and physics to determine the cause and the manner of a fatality.

And to really establish right away how crucial and just how complex these classifications are for the justice system, we have to start with a case from 2015 that ignited a huge controversy in Baltimore.

That would be the tragic death of Freddie Gray.

This scenario is it's the perfect foundation for this discussion.

Why is that?

Because it hinges entirely on the distinction between an accidental injury and criminal negligence.

It really forced the forensic pathologist to make a very specific and very heavy legal determination.

So walk us through the sequence of events that led to that final ruling by the medical examiner.

Okay.

So Mr.

Gray was a 25 year old man who was arrested in Baltimore.

He was handcuffed and placed into the back of a police transport van.

Right.

And our sources detail a chaotic and really disturbing sequence of stops.

Okay.

Early on, Gray could be heard yelling and banging inside the vehicle, so much so that the van was visibly rocking.

So there's a struggle happened.

The significant one.

Yeah.

The driver made two separate stops to apply more restraints, first leg restraints, then ankle cuffs, specifically to stop him from moving.

At that point, the protocol was followed.

He was slid into the van belly down head first.

So he was already fully restrained and secured, yet the ride kept going and there were more stops after that.

That's right.

There was a third stop, then a fourth stop where the driver actually called for a wellness check.

Yeah.

And what did they find?

That's when Mr.

Gray was found lying on the floor, belly down, saying he couldn't breathe.

He said he couldn't get up and that he urgently needed medical help.

Wow.

Then there's a fifth and final stop.

He was lethargic, but still kneeling.

But when the van finally got to the Western District headquarters, Mr.

Gray was found kneeling, but he was completely unresponsive.

He was no longer breathing.

That progression from alert and agitated to completely unresponsive is just a chilling timeline of deterioration.

What did the forensic pathology find when he was finally examined?

The initial medical exam showed he'd suffered a severe neck injury and a pinched spine.

He had emergency surgery, but died a week later from cardiac arrest that stemmed directly from those injuries.

OK.

The critical step came during the forensic autopsy.

The medical examiner concluded that, based on the progression of his symptoms and the timeline, the severe neck injury had to have happened while he was in custody during that transport in the van.

And this is where the crucial element comes in.

The thing that shifted this case from a tragedy to a potential crime,

the availability or lack thereof of safety procedures.

Exactly.

The medical examiner's report noted that safety equipment, specifically a seatbelt or harness, was available in that van.

But it wasn't used.

It was not used to restrain Mr.

Gray.

The ME determined that the injury to a vulnerable person during a routine vehicle operation, it wasn't an accident.

Why not?

Because the police failed to follow their own established safety procedures.

That failure to act, that act of omission, or what amounts to gross negligence, meant the manner of death was certified as homicide.

Wow.

That one decision, just distinguishing between a true accident and a death caused by a reckless disregard for safety, perfectly illustrates why the forensic pathologist's role is so central to the entire justice system.

That case just perfectly demonstrates that the determination of death is the absolute starting point for a criminal inquiry.

And the person leading that inquiry is the forensic pathologist.

So let's dive into section one, the core role of the forensic pathologist in scene investigation.

Right.

So forensic pathologists, they operate under the umbrella of the medical examiner, or ME, or the coroner's office.

And they have the fundamental responsibility of determining the cause and the manner of any unexpected, suspicious, or violent deaths.

They're kind of the expert bridge between the science of the body and the needs of the legal system.

We hear the titles coroner and medical examiner so often, you know, in media, but they are absolutely not the same thing.

You mentioned the distinction.

Can you really clarify how different those two offices are?

Yeah, this is a huge point of confusion.

A coroner is typically an elected official.

Elected, so they answer to voters, not a medical board.

Exactly.

And critically, a coroner may or may not even have a medical degree or any scientific training.

Oh yeah, the position actually dates back hundreds of years to King Richard I of England.

We're talking 1189 to 1199.

And the original duty was purely financial.

Financial.

To collect money and personal assets from the deceased for the crown.

So it started as an accounting role, and in some places it's still just an administrative or political job.

Precisely.

The medical examiner, on the other hand, is almost always an appointed official and in nearly all cases is a board certified physician with specialized training in forensic pathology.

And that medical training is the key difference.

It's everything.

Both offices, you know, they share the legal duty of certifying the cause and manner of death on the death certificate, but only the appointed trained pathologist is qualified to perform an autopsy.

Okay, wait.

If the coroner is an elected non -physician official, does that mean they could like hypothetically overrule a trained pathologists medical findings?

That is an excellent and critical question.

And the answer in some coroner run jurisdictions is yes.

While the pathologist determines the medical cause like a severe stab wound to the heart,

the coroner can have the final say on the manner, homicide, suicide, accident.

That potential conflict is huge.

It is.

And it's precisely why many states have moved toward the ME system, which is medically led, instead of the historical coroner system.

Okay, so given the sheer number of cases, a pathologist can't be at every single scene.

How does the initial scene investigation gather the information they need?

That initial work is delegated to trained ME or coroner investigators.

They work hand in hand with law enforcement and their first priority is absolute protection of the overall scene and the body.

The goal is to secure the location, prevent any contamination or degradation of evidence.

Only after that is the body removed following very specific medically acceptable procedures.

What are these investigators looking for right away?

I mean, they must be searching for really subtle signs that tell a story before the body is even touched.

They are.

They're looking for preliminary indicators of trauma.

For instance,

tiny little bruises along the upper lip might immediately suggest smothering.

Okay.

Or say a victim has a black eye, but the bruising is perfectly limited just to the eyelids.

Yeah.

That often implies the trauma came from inside the head, like a sudden impact or internal bleeding, not from an external punch.

And what about something like bleeding from the ear?

That can look minor, but it's often a really serious sign of a basal skull fracture.

So the documentation seems paramount because the pathologist is basically recreating events from just what's recorded.

It is the foundation of the entire case.

The preliminary reconstruction needs meticulous documentation of everything.

Blood spatter and flow patterns, they have to be photographed and sampled.

They search for discarded evidence, tire marks, shoe prints, fingerprints, and of course the suspect weapon.

You mentioned there are specific protocols for handling a body, especially in a firearm death, before it gets moved.

Yes.

With firearm deaths, before the body is shifted at all, investigators have to document the blood spatter directionality.

They check for any trace evidence, like hair or fibers.

Then the next vital step is to immediately place paper bags over the hands and secure them at the wrist.

Paper bags?

Not plastic.

I mean, a plastic bag seems like the go -to for preserving evidence.

And that's a common thought, but it would actually destroy the tiny evidence they need.

That level of detail is incredible.

Why paper?

It's absolutely critical.

Paper bags are used specifically because they allow air to circulate.

They prevent moisture condensation, which is inevitable inside a plastic bag.

That condensation would rapidly degrade or just destroy crucial trace evidence transfer DNA,

hair, fibers, or delicate gunshot residue particles.

And finally, the documentation has to include negative findings.

That sounds a little counterintuitive.

Negative findings just means photographing and documenting areas on the body where injuries are not apparent.

Why is that so important?

It proves the thoroughness of the examination, and it preempts any defense arguments later that those areas were never even checked.

The photographer has to use a scale in every single shot, overall medium close -up, to make sure they don't get so focused on the trauma that they miss documenting the undisturbed skin.

That's often just as important.

Okay, so once the scene investigation is complete and the body's been removed, the investigation moves into the lab for the postmortem examination, or the autopsy.

Let's move to section two, the autopsy.

What is the fundamental difference between the two main types of autopsies?

Fundamentally, an autopsy is just a postmortem examination, meaning after death,

but they have very different goals.

The clinical or hospital autopsy that focuses on internal organs.

It's to confirm diagnoses, see how far a disease progressed, and evaluate if therapy was working.

Its audience is really the medical community.

And the one we're focused on is the forensic or medical legal autopsy.

That's the definitive one for the courts.

Its sole goal is to determine the cause and manner of death for use in legal proceedings.

This type of autopsy involves a really rigorous effort to correlate the external injuries and internal findings with the crime scene.

Like matching a wound size to a potential weapon.

Exactly that.

Or confirming the position of a body after an injury.

Since this documentation is often the final word on the victim's physical state, how strict is that documentation or process?

It is mandatory, down to the finest detail.

The report has to meticulously record the date, time, and place of the exam, who performed it, and everyone who was in the room.

Every single injury must be photographed, always with a scale.

And again, those photos of uninjured areas are just as important.

And this is all because once the body is buried, the window for evidence collection is permanently closed.

That report and those photographs become the only evidence.

So let's talk about the specific evidence that's routinely collected during the autopsy and sent to the lab.

The pathologist has a whole checklist of samples.

This routinely includes the victim's clothing, preserving any cuts or tears, fingernail scrapings or clippings, head and pubic hair comings, and a bliggle swab for DNA.

That's the cheek swab, right?

Right.

And in cases with suspected sexual assault, vaginal, anal, and oral swabs are mandatory.

What about in a shooting?

If the victim was shot, any recovered bullets or fragments are collected very carefully to protect the forensic markings.

Swabs for touched DNA or saliva are taken from areas like the breasts or genitalia.

And finally, hand swabs are taken from shooting victims for gunshot residue analysis.

Even if it's a suspected homicide?

Even then.

Just in case the victim fired a weapon themselves.

That routine checklist just emphasizes the massive forensic value of a body.

Let's walk through the actual procedure, starting with the external examination.

The external exam is the first broad overview.

The pathologist notes the general characteristics, sex, height, weight, hair color, physical condition.

They check the body and the clothing, making sure any damage to the clothing lines up with the location and size of injuries on the body.

They're also looking for long -term indicators of the victim's life, I imagine.

Exactly.

They document tattoos, scars, and, critically,

any puncture or track marks that are telltale signs of chronic drug abuse.

Mm -hmm.

They also have to note any medical interventions, like chest tubes or IV lines from resuscitation efforts.

So those aren't mistaken for injuries from an assailant.

Okay.

They check the mouth, nose, and ears for vomit, blood, or irritations in the nose that might indicate drug sniffing.

And how do they visually classify the injuries on the skin?

They classify them as abrasions, which are scrapes, contusions, which are bruises, lacerations or tears, and sharp injury wounds.

A really vital external check is for small pinpoint hemorrhages in the eyelids.

These are known as patechiae.

Tell us more about patechiae.

Why are these tiny burst capillaries in the eye so important?

Patechiae form when there's extreme pressure or an obstruction that restricts blood outflow from the head.

This causes the fragile capillaries to burst and leak blood into the tissues.

And their presence indicates what?

Their presence is a very strong indicator of strangulation, whether it's manual or with a ligature.

While they can appear in other ways, like a severe coughing fit, their presence in a suspicious death raises an immediate red flag for asphyxia.

Let's move to firearm injuries and the telltale markings of discharge.

Okay.

So when a firearm is discharged, it releases hot gases,

burned and unburned gunpowder, and soot.

These create characteristic markings on the skin around the bullet hole.

And this is called stippling.

It's known as stippling or tattooing.

It's what happens when the gunpowder actually impacts the skin.

The forensic pathologist meticulously analyzes the span and the density of this stippling.

And that analysis is critical for determining the range of fire.

Absolutely.

The range approximation is often the single most important factor in distinguishing a homicide from a suicide.

How so?

Well, if there is dense, close stippling, it means the gun was fired at close range.

If the stippling is very broad and sparse, the distance was greater.

And if there's no stippling at all, it suggests the gun was fired from several feet away, which generally rules out a self -inflated wound.

Before the pathologist even makes an incision, x -rays are usually taken.

What do those films reveal?

X -rays are routine, especially in gunshot and stab wound cases.

They can locate any small projectile fragments or weapon tips still lodged deep inside the body.

They also help map the exact path of the projectile or the blade.

And beyond that, they are invaluable in suspected child abuse cases.

X -rays can reveal healed or fresh bone fractures that point to a clear pattern of historical abuse that would be invisible to the naked eye.

Now for the internal examination, you mentioned a distinctive incision they use to start this work.

Yes, the definitive first cut is typically a Y -shaped incision.

It begins high on the top of each shoulder, runs down the front of the body, meets at the center of the chest, and continues down to the pubic bone.

And that gives the maximum access.

Exactly.

It provides the maximum access to the chest and abdominal organs.

To examine the brain, a separate incision is made from behind one ear over the top of the head to the other ear.

This allows the scalp to be peeled back and the sole cap to be removed.

Once open, what happens during the organ analysis?

Every single organ is analyzed.

Each one is way dissected and sectioned.

And microscopic examination of tissue samples can reveal chronic, often hidden conditions.

For example, examining the lungs or liver can confirm long -term intravenous drug abuse by detecting fibrous tissue.

They're also looking for pre -existing conditions that might have contributed to the death.

Like what?

Things like congenital heart malformations or pulmonary edema.

That's a buildup of fluid in lungs,

which is a common finding in victims of chronic cocaine and amphetamine abuse.

And the analysis of stomach contents must be crucial, both for poisoning and for estimating the time of death.

It serves both functions, yes.

If poisoning is suspected, the stomach is inspected for partially digested or dissolved pills.

More generally, the state of the last meal helps estimate the time elapsed since ingestion.

Interesting.

And, interestingly, finding a very large number of pills in the stomach usually suggests suicide.

Accidental overdoses typically involve more gradual consumption.

Let's talk about toxicology.

What specimens are considered essential?

Essential specimens include blood, stomach content, bile, urine, brain matter,

liver tissue,

and the clear fluid from the eyeball, which is called vitreous humor.

The collection process itself is very sensitive.

Blood has to be taken from areas with the least chance of contamination.

It should never be drawn from body cavities where it could have mixed with other fluids.

You mentioned that analyzing post -mortem drug levels is complicated by a phenomenon called post -mortem redistribution.

This sounds like a huge hurdle.

It is the core challenge.

Post -mortem redistribution is this phenomenon where, after circulation stops, drugs that were stored in high concentrations in deep organs, like the liver or muscles, start to leach back into the blood.

So the levels in the blood could be misleading.

Exactly.

A high level found in the blood might have occurred after death, not from toxicity before death.

So how do they counteract this to get a reliable reading?

The best practice is to collect blood from multiple distant sites for comparison.

Ideally, they'll collect blood from the inferior vena cava in the lower abdomen and also from the superior vena system above the heart.

And by comparing the levels?

By comparing the levels in these different spots, they can better gauge the true concentration at time of death and account for the effects of redistribution.

When pathologists interpret these drug levels, how do they know if a level is therapeutic or toxic?

They rely on extensive published pharmacological data.

Sometimes it's obvious, you know, with depressants and alcohol, but sometimes even low levels are fatal.

For instance?

Consider cocaine -induced sudden death.

This often results not from the immediate dose, but from structural changes to the cardiovascular system caused by years of chronic use.

For these users, even a seemingly trivial amount of the drug can trigger a fetal cardiac event.

Is testing for obscure poisons a routine thing?

No.

General poison testing is not routine.

It's expensive and time consuming.

Specific tests are only performed when physical signs during the exam point to a specific substance.

What are some of those visual indicators that would make a pathologist look for a specific toxin?

A bright cherry red discoloration of the skin and internal tissues immediately raise a suspicion of carbon monoxide poisoning.

Cyanide toxicity can produce a slightly pinkish color and is often accompanied by the distinct smell of burnt almonds.

And finally, any corrosion or chemical burns around the lips suggest the victim ingested a highly caustic acid or alkaline substance.

Once all the evidence is collected and analyzed, the forensic pathologist has to synthesize it all into two final crucial determinations.

Let's move to section three.

Determining the cause and manner of death.

Starting with the cause of death.

The cause of death is defined as the injury or disease that initiates the series of events that ultimately ends in death.

In violent deaths, the pathologist has to trace that chain of events all the way back to the original injury.

So if a victim survives an assault but dies months later from complications, like an infection from the wound.

The original fatal wound remains the underlying cause of death, even if the immediate cause was Let's break down the common categories.

Starting with blunt force injury.

Anything caused by a non -sharpened object like a bat, a pipe, or a fist.

Okay, so when skin is hit hard enough to overstretch and tear, you get a laceration.

The key characteristic of a laceration is that the tissue is crushed and torn.

You'll see abrasions around the wound and often tissue bridging torn strands of tissue connecting the two sides of the wound inside.

And a bruise.

If the force crushes tissue beneath the skin without breaking the surface, it ruptures blood vessels and that creates a contusion or a bruise.

We tend to think of forensics as being absolutely precise, but when it comes to bruising,

can you really age a bruise by its color like you see on TV?

Forensic pathologists strongly caution against that.

Attempting to age bruises based on color changes, blue, green, yellow, is inherently difficult, highly variable, and generally unreliable in court.

So that's mostly a myth.

For legal purposes, pretty much.

It's also vital to remember that not all contusions are visible externally.

Significant internal bruising in deep soft tissues might be missed without a thorough internal exam.

Can the weapon that caused the injury sometimes leave an identifiable signature in the bruising?

Occasionally, yes.

A contusion can briefly exhibit the pattern of the weapon.

The distinct impression of a ring, the weave of a belt, or the imprint of a shoe heel if the victim was stomped.

But that's a fleeting thing.

Very fleeting.

The pattern quickly dissipates as the color changes and the blood spreads, usually within a few hours.

Okay, moving to short -force injuries, knives or blades.

How does the pathologist differentiate between a cut and a stab?

It's all about dimension.

A cut is an injury that is longer than it is deep, from drawing the blade across the skin.

Okay.

A stab is an injury that is deeper than its length, from thrusting the weapon inward.

Crucially, in both types, the tissue is cleanly sliced, not crushed or torn like a laceration.

And what are defense wounds?

They seem like an obvious clue to the violence of a struggle.

Defense wounds are critical indicators.

They are typically found on the forearms or the palms as the victim raises their arms to block the assault.

They can also appear on the legs if the victim was kicking out.

And a lack of them is also a clue?

The lack of any defense wounds at all can be just as telling.

It could suggest the victim was unconscious, restrained or ambushed.

The case of Harold Shipman, Dr.

Death, really underscores how vital toxicological work is, especially when you're dealing with hidden violence.

Oh, absolutely.

Shipman, a UK physician, was systematically killing his elderly female patients with lethal doses of heroin or morphine.

And he got away with it for years.

For years.

Because he was the one certifying the deaths as natural.

The case only broke open because of an 81 -year -old patient, Kathleen Grundy.

A forged will surfaced, leaving all her money to Shipman.

And that immediately suggested foul play where none was suspected.

Exactly.

The legal inquiry led to Mrs.

Grundy's body being exhumed, and toxicology revealed a lethal, undeniable quantity of morphine.

Retrospective audits estimated he had killed at least 236 patients.

The toxicological evidence, confirmed across multiple exhumed bodies, proved the cause of death was acute drug overdose, transforming what were once considered natural deaths into homicides.

Let's shift to asphyxia, which is interference with oxygen intake.

This is the primary cause of death in fire scenes, right?

That's right.

Because the primary killer in a fire isn't the heat.

It's the extremely toxic gas carbon monoxide, CO.

When it's inhaled, CO binds aggressively to hemoglobin, the protein that carries oxygen in your blood -forming carboxyhemoglobin.

This binding is so strong, it just stops oxygen from reaching the brain and vital organs.

And the level of CO in the blood can prove whether the victim was alive and breathing during the fire?

That's the forensic clock.

Carbon monoxide is only inhaled while you're alive.

It can't build up after circulation stops.

High carboxyhemoglobin levels unequivocally mean the person was breathing smoke.

And there's another indicator.

The presence of soot.

Soot particles are often seen deep in the airway, the larynx, trachea, even the lungs, or sometimes swallowed into the esophagus, confirming the victim was alive and inhaling.

What are the key differences a pathologist looks for between death by hanging and death by manual strangulation?

Death from hanging is typically from the cessation of blood flow to and from the brain because the vessels are compressed.

Hanging victims might show patechiae and facial swelling.

Okay.

However, the fracture of the hyoid bone, this delicate U -shaped bone at the base of the tongue and the thyroid cartilage, is rare in hangings.

But it's common in manual strangulation.

It is very common in manual strangulation where direct crushing force is applied to the neck.

So the condition of that hyoid bone is a major distinguishing factor.

It's a major piece of evidence.

And documenting the hanging scene itself is vital.

They have to record the victim's exact position.

And to preserve the knot, they have to cut the noose far away from the knot itself so an expert can analyze it.

And finally, under asphyxia, we have smothering.

Smothering involves physically blocking the mouth, nose, or internal airway, often with a hand or a pillow.

It's overwhelmingly ruled homicidal, only occasionally accidental.

Let's discuss gunshot wounds again.

We know the range of fire is critical, but what does the pathologist need to ensure about the wound track?

Determining the projectile's path, or wound track, is mandatory.

They have to meticulously document its course through the body, noting every organ and tissue it passes through and recover all projectiles.

And they have to handle those fragments carefully to protect the forensic markings, the rifling marks, which are essential for ballistics.

And what about contributory causes?

Right.

The pathologist has to be careful.

Complications that arise weeks later, like an infection, are considered contributory causes.

But the original gunshot wound remains the underlying cause of death.

Lastly, let's touch on substance abuse as a cause.

If drug abuse is chronic, the classification can be surprising.

Yeah, routine testing for drugs is common.

Death can be direct, from toxicity or indirect, from impaired judgment leading to an accident.

But what about chronic use?

When death results from the chronic effects of drug use, like long -term deterioration of the heart or liver, the death is often labeled natural causes, not accidental or suicidal.

Now we come to the manner of death.

This is the culmination of the whole investigation and what directly informs the legal system.

Our sources list five classifications.

Correct.

The manner of death is about the circumstances that led to the fatal result.

The five official categories are homicide, suicide, accidental, natural, or undetermined.

Let's start with homicide.

Homicide is the classification for a non -accidental death that results from the grossly negligent, reckless, or intentional actions of another person.

Like we saw in the Freddie Gray case, even an omission can satisfy that negligent actions requirement.

To determine suicide, how certain does the pathologist have to be about the victim's intent?

They have to be certain that the individual carried out the act alone with a lethal intention.

If there's genuine doubt, it can't be classified as suicide.

It usually defaults to accidental or undetermined.

What details help distinguish a gunshot suicide from a homicide?

Well, personal history and a suicide note are relevant, but the physical wound is key.

The wound has to be physically accessible to the victim.

So a shot to the back?

A shot to the back of the head or body strongly suggests homicide.

The most common self -inflicted wounds are to the temple, mouth, forehead, or chest.

And it's important to know multiple shots are possible in determined victims.

Next, accidental death.

Accidental death means there was no intent to cause harm and no gross negligence.

Things like traffic accidents,

environmental exposure, or drug overdoses where there's no intent to die.

But the pathologist has to be sure.

Always.

They have to make sure the scene wasn't manufactured to hide homicide or suicide.

And how is the distinction made between accidental and natural causes?

Natural death results from disease or chronic environmental abuse, long -term smoking,

alcoholism.

The difference can be subtle.

An acute overdose in a first -time user might be ruled accidental.

But if the victim is a chronic alcoholic and dies of liver failure— That's natural.

That would likely be classified as natural due to the prolonged self -inflicted decline.

And finally, undetermined.

This is the fallback.

A death is only ruled undetermined when a rational classification just can't be established.

There's a complete lack of physical or toxicological findings to clarify the circumstances.

Here's where it gets really interesting.

The case of the Sheridans illustrates the tremendous pressure and potential for error in these classifications.

It really does.

The Sheridans, a married couple, were found dead in their New Jersey home in 2014.

The bedroom was on fire, gasoline had been poured on the carpet, and knives were present.

Joy Sheridan had 12 stab wounds, one to the aorta, and her death was quickly ruled a homicide.

And her husband, John?

John Sheridan had five stab wounds.

But crucially, he had soot in his lungs and high carbon monoxide in his blood, confirming he was alive when the fire started.

The prosecutor's office quickly ruled his death a suicide.

But the physical evidence just didn't support that easily?

Precisely.

The family hired a renowned forensic pathologist who pointed out massive inconsistencies.

First, the knife that caused John's narrow deep wounds, some up to two inches deep, was never found.

Never found.

Never found.

And second, five deep thrust wounds are highly unusual for suicide.

The depth and nature of the wounds suggested a violent sustained attack.

So the controversy was whether the state could rule it a suicide without a weapon and with such an unusual wound pattern?

Yes.

The sheer force required and the implied defensive nature.

It created huge doubt.

In January 2017, the state medical examiner's office formally reversed course and changed John Sheridan's manner of death from suicide to undetermined.

It's a powerful example of how critical thinking has to prevail when evidence conflicts with an easy answer.

That discussion really reminds us of the difficulty of establishing a timeline.

Let's move to section four, estimating time of death or the postmortem interval, PMI.

PMI is arguably the most challenging part of the initial investigation because a pathologist can never give an exact time of death, only a broad approximation.

Right.

And this approximation is based on three key short -term physiological conditions.

Algor mortis, lyr mortis, and rigor mortis.

And it's always balanced with witness accounts.

Okay, so let's start with algor mortis.

That's body cooling, right?

Exactly.

Algor mortis is the process where the body loses heat until its temperature equalizes with the ambient environment.

This requires recording two things at the scene, the environmental temperature and the internal body temperature.

And what's the typical rate of cooling?

Under average conditions,

say 70 to 72 degrees Fahrenheit,

the body loses heat at an estimated rate of one to 1 .5 degrees Fahrenheit per hour until it hits room temperature.

But that rate is profoundly susceptible to external factors, making it just an approximation.

Extremely susceptible.

Heavy clothing insulates the body and slows the rate.

A small body cools much faster than a large, obese body.

High winds, cold water, they all skew the rate dramatically.

It's only useful for a rough initial guess.

Next, we have liver mortis or levity, which is the settling of blood.

Right.

Liver mortis happens once the heart stops pumping.

Gravity pulls the blood down to the parts of the body closest to the ground, causing a distinct bluish -purple discoloration in those areas.

And what's the timeline for levity?

The onset begins about 20 minutes to three hours after death.

It continues to develop, getting darker, for up to 16 hours.

At that point, the levity is considered fully fixed.

Explain the difference between blanching and fixed.

Initially, if an investigator presses a finger on a levity area, the color will fade temporarily because the blood can still be pushed out of the vessel.

That's blanching.

Okay.

As time passes, the blood cells break down and the coloring becomes fixed in the tissues.

You can't press it out anymore.

If some areas blanch and some don't, the pathologist can get a better idea of the time frame.

And this phenomenon is key for determining if the body was moved.

Absolutely.

If the body is found on its back, but the levity is fixed across the abdomen, it clearly shows the body was moved after death, but before the levity was fully fixed.

Finally, rigor mortis, the stiffening of muscles.

Rigor mortis is a chemical change, a lack of ATP in the muscles, which causes them to become rigid.

Under average conditions, this rigidity evolves over the first 24 hours and then disappears over the next 12, resolving after about 36 hours.

How does rigor mortis indicate post -mortem movement?

Rigor develops in the exact position the body was in at the time of death, essentially freezing that pose.

If investigators find a body in a position that defies gravity, like an arm raised in the air, it strongly indicates the body was moved after rigor had set in.

What can speed up or slow down rigor?

Heat speeds it up significantly, cold slows it down, and pre -death factors matter too.

Extreme physical activity right before death accelerates it, and people with less muscle mass infants, the elderly, might have incomplete rigor.

Beyond the big three, what other chemical changes do pathologists use for PMI estimation?

They look at potassium eye levels.

After death, cells in the eyeball break down and release potassium into the ocular fluid, the vitreous humor.

So they draw a sample from the eye?

Yes, a clean, bloodless sample from one eye, and ideally a second sample from the other eye an hour or two later.

So they're measuring the rate of release, not just the total amount.

Exactly.

The vitreous humor is less susceptible to contamination than blood, so the potassium release rate is a relatively reliable chemical clock.

It helps approximate the time of death, though it's still dependent on ambient temperature.

And when all those short -term methods fail, we enter the phase of decomposition.

Once decomposition sets in, the methods we just discussed become useless.

Decomposition involves two simultaneous processes.

Autolisis and putrefaction.

Describe autolisis.

Autolisis is the internal process of self -digestion by the body's own enzymes.

They begin to break down the body's cells from the inside out.

And putrefaction is the microbial breakdown.

Putrefaction is decomposition caused by microorganisms, mainly bacteria from the bowel.

This process is accompanied by significant bloating, discoloration, usually starting as a green tint in the abdomen and a foul smell from the gases.

The visual markers of advanced decomposition can be quite stark.

They are very distinct.

As gases accumulate, the skin begins to blister and peel away, a process called slippage.

In advanced cases, the skin of the hands and feet can literally detach in one piece like a glove.

And the formation of adipocere is a specialized form of decay.

Adipocere is a waxy, white, or gray substance that forms in fatty tissues when decay happens in moist, low -oxygen environments.

It takes about three months to develop.

Its presence is significant because it can protect the underlying tissue, preserving remains for much longer.

When investigators are faced with severely decomposed, fragmented, or skeletonized remains, where none of that remains, they turn to Section 5, the specialized experts, starting with forensic anthropology.

Forensic anthropology is the specialized study of human skeletal remains for identification and examination.

Bones are incredibly durable.

They can resist breakdown for decades, retaining crucial individual characteristics.

How do they locate clandestine graves or scattered remains?

The site is treated as a complex crime scene.

They use a variety of tech.

Aerial photography, metal detectors, ground -penetrating radar, instruments that detect decomposition gases, and, of course, the indispensable cadaver dogs.

And once located, the excavation must be extremely meticulous.

Absolutely.

All bones and evidence are tagged, photographed in place, sketched, and located with GPS.

This spatial mapping is crucial because bones are often scattered, and their relationship helps determine if the death occurred there.

Let's discuss the four primary characteristics anthropologists try to determine.

Sex, age, ancestry, and height.

How do they determine sex?

Sex is determined primarily by the size and shape of the pelvis and the skull.

The pelvis is the most reliable indicator.

Can you describe those pelvic differences visually for us?

Yeah.

The female pelvis is adapted for childbearing, so it has a wider, more circular opening, a short and wide sacrum, and a subpupic angle that's near 90 degrees.

And the male pelvis?

Is narrower, with a longer sacrum, and an acute subpupic angle that's less than 90 degrees.

Male skulls are also generally larger and heavier, with more pronounced brow bones.

How is age estimated from remains?

It varies a lot by developmental stage.

For infants, they look at long bone length and tooth formation.

For children and adolescents, it's about the fusion of the epithelial regions, the growth plates in the bones.

These fuse at known average ages, providing a reliable range.

And for adults, after those growth plates have fused?

After about age 21, it relies on degenerative changes.

A common marker is the surface of the pupic symphysis, where the two halves of the pelvis meet.

It changes from a rough surface in young adults to a smoother one over time.

The determination of ancestry, or race, is often the most challenging.

It is difficult, as these features overlap a lot.

Anthropologists look at skull characteristics like the eye orbits, circular and mongoloid descent, oval and Caucasoid, square and negroid.

The nasal cavity also varies.

And a unique feature is shovel -shaped incisor teeth, common in Asian and Native American descent.

Finally, how is height estimated?

Height is estimated by measuring the maximum length of long bones, particularly the lower limbs like the femur.

This requires using known equations that are specific to the determined sex and ancestral population of the remains.

Beyond identification, what other contributions do anthropologists make?

They frequently create facial reconstructions.

This involves placing clay over the actual cranium,

using depth markers to approximate soft tissue layers.

This visual composite can be distributed to generate leads.

They are also indispensable in mass disasters, where they sort and identify fragmented remains.

The John Wayne Gacy case provides a historic example of an anthropologist sorting through absolute chaos.

It was a monumental task, undertaken by the renowned forensic anthropologist Clyde Snow.

Gacy had buried 28 young men in the crawlspace under his house.

The remains were highly degraded, fragmented and often mingled.

How did Snow even tackle the challenge of identifying 28 individuals from co -mingled bones?

First, Snow had to meticulously perform a 35 -point examination on each skull and long bone to ensure he correctly attributed every fragment to a unique individual.

Then he used long bone measurements, particularly the femur, to estimate the victim's heights.

This was a crucial step that helped narrow the search against missing persons' reports.

But his work went beyond just height and sex, didn't it?

Oh yeah.

Snow was able to spot unique skeletal defects, a heeled fracture, or signs on a shoulder blade that pointed to a victim's behavior, like being left -handed.

The use of a forensic sculptor for facial reconstruction also helped generate leads.

Though, despite all that effort, nine of Gacy's victims remained unidentified.

Let's turn to our final specialized expert in Section 6.

Forensic Entomology, the study of insects which takes over when the body has been decomposing for more than 48 hours.

Entomology is primarily used to estimate the post -mortem interval, PMI, when the physiological markers are no longer useful.

Insects are remarkably accurate biological clocks because their life cycle is highly predictable under specific conditions.

And the primary indicator here is the blowfly.

Yes.

The necrophilius insects, blowflies, the metallic green or blue ones, are generally the first to arrive, often within 24 hours.

They are attracted to the moisture and scent and can lay up to 2 ,000 eggs, usually in natural orifices or open wounds.

And these hatch into maggots.

They hatch into larvae, or maggots, which feed on the tissue, often gathering in what's called a maggot mass.

How does the entomologist use this life cycle to approximate PMI?

They approximate PMI by determining the developmental stage of the most developed fly larva found on the body.

The blowfly life cycle is a predictable sequence.

Egg, larva stage one, stage two, stage three, post -feeding stage, puparium, and finally, the adult fly emerges.

So they can backtrack from there.

By measuring the length and stage of the most advanced specimen, they can backtrack using known growth rates to pinpoint a range for when the eggs were laid.

This works exceptionally well for timelines up to about one month.

So newly emerged adult flies or empty pupil cases are a massive clue.

They indicate that at least one full life cycle has been completed on the body, providing a minimum PMI estimate.

Later stages attract other species, like cheese skippers, which appear when the body is drying out.

Since insects are cold -blooded, environmental factors must heavily complicate the calculation.

There are massive variables.

Cold temperatures drastically slow down development, while a hot, humid environment speeds it up.

Geographic location, local climate, weather, and even the presence of drugs in the body all affect the time required for each stage.

Beyond the blowfly, the sequential arrival of different insect species, insect succession, also helps with the PMI estimation.

Absolutely.

The insects arrive in predictable waves.

First, the necrophilias insects like blowflies.

Second, the predators arrive to prey on the first group of beetles feeding on the maggots.

Then come the omnivores like ants and wasps.

And finally, the indigenous insects like spiders whose presence is just coincidental.

The presence or absence of a specific species provides temporal milestones.

Can insects provide information beyond just the time of death?

Yes, quite a bit.

Insects naturally colonize the moist orifices first.

If colonization is found heavily concentrated somewhere else, say on the forearms, it strongly indicates the location of open wounds, possibly defensive wounds.

Also, since the insects feed on the flesh, they accumulate any drugs present in the body.

If the blood is too decomposed for toxicology, the maggots themselves can be analyzed for drugs.

So the collection protocol sounds crucial for maintaining the integrity of this evidence.

It's essential.

The area has to be thoroughly photographed.

Specimens have to be collected from each distinct area of the body and labeled meticulously.

Ideally, this is done by an expert entomologist who knows how to preserve them properly.

The Danielle Van Dam murder case provided a pivotal example of how conflicting entomological evidence can become the central battleground in court.

It did.

Danielle Van Dam's body was found highly decomposed three and a half weeks after she disappeared in 2002.

David Westerfield, her neighbor, was the primary suspect.

And because Westerfield had been under constant police surveillance starting on February 4th, the exact time of death was paramount.

If she died after that date, Westerfield was likely innocent.

And the entomology presented conflicting timelines.

It did.

One defense expert estimated death occurred between February 16th and 18th, which would have exonerated him.

However, the prosecution's experts argued that the hot, dry weather at the dump site caused mummification of the remains, which delayed or even inhibited fly colonization.

So that made it possible she died earlier.

It made it scientifically possible that death occurred before February 4th, directly linking Westerfield to the murder.

The ability to argue for and defend the variable effect of the environment on insect colonization was pivotal in securing the murder conviction.

So what does this all mean?

We've navigated the entire process of death investigation, moving from the scene to the microscopic details of the body and the life cycle of the blowfly, all tied together by the forensic pathologist.

The key takeaway is that death investigation is a dynamic, multi -layered process where no single piece of evidence stands alone.

Everything hinges on three major pillars.

First, determining the cause and manner of death, which is the primary duty of the forensic pathologist.

Second, approximating the time of death, or PMI, which relies on those short -term physiological markers, Algor, liver, and rigor mortis, and the longer -term analysis provided by forensic entomologists.

And third, establishing identity, which is crucial in cases of severe decomposition or trauma, and that's handled by forensic anthropologists, odontologists, and DNA analysts.

It's an intersecting puzzle where all the specialized evidence has to correlate to establish the truth.

And thinking back on the complexity of PMI, especially with the reliance on variables like temperature and body fat, the fact that determining time of death is less a precise calculation and more an intersectional puzzle involving chemistry, physics, and biology, where the environment is the ultimate variable.

That is the final provocative thought we want to leave you with.

Forensic science is driven by this desire for certainty, yet the most minute detail, a partially digested meal, the precise ambient temperature, or the species of fly larva present, can literally shift a homicide timeline by weeks.

The challenge for the legal system is accepting that scientific certainty, particularly in the face of these natural variables, is often a matter of statistical probability and meticulously argued expert opinion rather than absolute unassailable fact.

A sobering and fascinating thought.

Thank you for guiding us through this essential but difficult subject.

My pleasure.

And thank you for joining us for this deep dive.

We'll see you next time.