Learn Something New Every Day – Lecture 20: Death Investigators

Decomposition happens when the absence of metabolism in the dead body causes cells to start dying and then they domino to cause the collapse of organs and body systems.

But if not for bacteria in our bodies, decomp would take much longer.

Essentially, on a normal day the average healthy human body has more bacterial cells on and in it than the total number of its own cells. But our bodies have checks to keep the numbers down (various forms of excretion, primarily, and our immune system) or to keep them contained to a particular area.

But after death all bets are off. It is a bacterial field day. There is nothing to contain the cells that can self-reproduce every 20 mins and, with unlimited access in all parts of the body to the entire body as an energy source, they get straight into massive and rampant reproduction. The bacterial frat party to end all parties. Thriving, changing, evolving bacterial processes long after the body is dead.

Thus, after death a body can potentially have more life in it than before.

So…if bacteria cobined to form super-organisms mabye they COULD create zombies from the living ‘sleeve’ of an ex-human being?

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Learn Something New Every Day – Lecture 20: Death Investigators

Oxygen deprived blood is a dark red colour. When it’s well oxygenated it is a brighter/vibrant red.

Veinous blood may look blue because of light diffusion through skin and livor mortis (lividity) makes the pooling of blood in a dead body look purple/blue for the same reason. So you’d expect someone suffering from carbon monoxide poisoning (where the blood fills with carbon monoxide and so has no room for oxygen) to have deep, dark red blood, right?

Not so. Their blood is cherry red (and victims of carbon monoxide poisonings take on a cherry red skin colour making them easy to diagnose).

This is because haemoglobin binds much better to C0 than 0 so as far as the blood is concerned it’s fully loaded (and therefore bright red) but oxygen can’t get a look-in and so the cells start to die.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Learn Something New Every Day – Lecture 19: The Science of Death

Hollywood (and fiction to a certain extent) is partial to ‘pretty death’. Fictional characters are often conscious to their last breath, calm, and really only weakened by their impending death. They utter a few final words, or offer a hand-squeeze before their eyes either close or go glassy and their head droops. Perhaps a small puff of air.

All very…pleasant and contained.

Real death is never, ever pretty.

Because function leaves voluntary muscles in favour of more vital organs, the person’s jaw often goes slack and their mouth falls open, their eyelids flutter half open (because opening or closing them takes muscular effort), dehydration causes mucus to collect in a throat they can’t clear and creates a tortured ‘death raggle’ gurgle, the blood leaves the skin for the core leaving it blotchy or cold to the touch, the heart rate and respiration can double causing agitation, confusion, anxiety, hallucination and restlessness. And that’s all without unpleasant wounds to content with.

Other Hollywood myths about death

- The same abandonment of voluntary muscle control is behind the popular myth that a dead person will automatically void their bladder and bowel — they will if it’s very full but not because death causes some kind of surge of peristaltic activity. It’s just that the spincters that keep the bowel and bladder closed may relax when the body centralises its resources elsewhere and so anything waiting to come out…does. But someone with little or nothing in their digestive system to excrete won’t.

- fingernails and hair do not continue to grow after death because that would require metabolism. The scalp and the cuticles shrinks and pull back revealing more hair follicle or nail length which can look like growth.

- the person attending the crime scene is unlikely to be the person undertaking an autopsy. They are two distinctive roles with particular skill sets and are often used to verify each other’s findings and so having your coroner also be your crime scene death investigator is only a fictional convenience.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Something New Every Day – Lecture 18 – Blood patterns

• How coagulation works – when a blood vessel is damaged or exposed, the lining produces proteins which attract the platelets which make up 1% of blood. The platelets turn sticky and clag together to plug the small wound. Once they’re all wedged in there, they themselves form a protein which reacts in the bloodstream to form insoluble protein strands called ‘fibrin’ and these (like fibreglass strands) bond together to seal the wound.
• What makes a blood pattern? Blood generally has a fixed surface tension and a particular viscocity that makes it tend to cling to itself if left unchanged (kind of like the classic ball of mercury). But when gravitational forces or impact forces are sufficient, they can break blood’s inherent surface tension/viscosity and cause the blood to break into multiple droplets, the size and number of which create different patterns that forensic serologist can use to determine what happened at a crime scene.
• Types of blood patterns
  • Passive – generally the result of gravity (dripping, pouring, pooling, streaking) or transfer
  • Spatter – droplets scattered on a surface. They result from a force in addition to gravity (eg: blunt force trauma, gunshot, knife wounds etc)
  • Altered – changed through natural clotting, insect activity, mixing with organic material, attempted clean-ups or the presence of an obstruction that interferes with the natural patterning (eg: a void)
  • Sattelite droplets are secondary droplets caused when a passive droplet impacts something (like the floor) and spatters off
  • Cast-off is the particular name given to the droplets that have come off the weapon and not the victim. These are used to determine the minimum number of strikes and the order that the strikes happened.
  • All splatter is spatter but not all spatter is splatter – Spatter is the term used when droplets of blood are scattered on a surface by the forces of a crime/incident. ‘Splatter’ is a type of spatter but it is only one configuration of spatter
  • How to make blood that both looks and feels real – 500ml powdered milk, slowly add 325ml water (stir until smooth), 1.5ounces red food colour, 25 drops green, 5 drops blue.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Something New Every Day – Lecture 18 – Blood patterns

Flies might excite entymologists in the crime lab but they can seriously muck up the work of the serology team. Flies in a crime-scene can ingest blood and regurgitate it, which alters the composition and nature of the blood and thus the evidence.

They also excrete the blood in tiny amounts that, if there are enough flies, can replicate a kind of blood spatter and misdirect crime scene analysts.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Something New Every Day – Lecture 17 – Fire and Explosion Forensics

Just like there are bomb detection dogs and drug detection dogs, there are also arson detection dogs. Trained canine noses can sniff out tiny quantities of known accelerant hydrocarbons even after extensive burning. They are much quicker to use in the field than in-lab chemical tests.

Even though a regular fire itself can produce hydrocarbons that the dogs will detect, it doesn’t matter because forensic methodology allows for ‘false positives’ in the field that can be ruled out later in the crime lab. So it’s better to have a dog tell you there might be accelerant to be found (and end up being wrong) than have no dog and no idea to look for it.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Something new every day – Lecture 17 – Fire and Explosion Forensics

Every explosion (except for nuclear ones) have a positive and negative phase. As the name suggests, the positive phase happens as pressure, heat and noise moves away from the site of the explosion and sometimes this is known as the ‘shock front’.

But right behind that is the negative phase which is caused when the sudden outward moving of pressure creates a vacuum behind it that sucks gasses and debris back toward the explosion.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Something New Every Day – Lecture 17 – Fire and Explosion Forensics

Demographic-wise, the most dominant occupation of arsonists who light fires in order to be ‘heroic’ and discover them are:  Security guards, volunteer fire fighters, nightwatch personnel, baby-sitters and…wait for it…

…volunteer librarians.

I have *no* idea why librarians particularly love to watch things burn. You’d think flames would be the natural enemy of someone who loves books.

 ‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Something New Every Day – Lecture 16 – Vehicular Accident Forensics

• There are 250 million registered vehicles in the USA
• Statistically, city streets are safer (by far) than country roads, but this is the combined effect of lower driving speeds due to congestion and increased traffic control in cities, and the greater distances to hospital for country areas on fatalities.
• Economic losses from motor vehicle accidents are US$200 billion a year and 33% of those are accidents involving alcohol.
• In MVAs, drivers will typically under-represent own speed and over-represent other speed but that’s not necessarily attempts to be duplicitous, can be the distorted perception of reality.
• Equipment failure is a very small cause of vehicular accidents
  • 48% – collision with another vehicle
  • 26% – collision with fixed objects
  • 12% – pedestrian impact
  • 11% – ‘non collision’ impacts
  • 2% – collision with non motorised vehicles
  • 1% – collision with train
  • 0.2% – collision with animal

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Something New Every Day – Lecture 15 – Structural Forensics

The impact of two fully-loaded 767 aircraft slamming into New York’s World Trade Centre in September 2001 was not what cause the buildings to collapse.

It was the fuel spill.

Forensic engineers determined that the thousands of gallons of aviation fuel that spilled as the two planes exploded consecutively caused fires on six floors of Tower One and nine floors of Tower Two that incinerated everything on those floors over the next hour or so.  Contents, occupants, steel supports, concrete floors, everything. Smouldering like a furnace.

As a result, each building effectively had a six- or nine-story ‘void’ within one hour of the impacts and whatever structure did survive was in no condition to withstand the weight of the (respective) 19 and 11 floors above them. The sudden impact of those 19/11 floors hammering down into the void was what caused each tower to pancake and collapse.

Like taking the legs out from under a timber house. The combined weight of the whole thing dropping was way too much for the rest of the building to withstand. Even though they’d technically withstood the impact of the planes.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Something New Every Day – Lecture 14 – Computer forensics & digital evidence

If you’ve ever wondered how it is that forensic computer experts are able to ‘recover’ supposedly deleted stuff from criminal computers, here’s how.

Most computers store files in ‘contiguous’ circles/tracks in the memory. Each tracks have a limited size and so a computer will find a ‘gap’ big enough for whatever file you’re working on and slot it in there. This is ‘fragemented’ filing.  After time you develop a whole bunch of smaller ‘slack’ spaces between the actual files. Active ‘de-fragging’ by users can minimise this and tighten up some of that slack space which reopens new space for bigger files again, but computers (for whatever reason) decide to store deleted and temp files in the slack space and you don’t know about it.

Forensic experts have software tools to let them access and review slack space. And if your great hacking heist or your 250 peadophilic images that you thought you’d deleted are littering your slack space then they’re there to be found.  It’s unlikely to be a full document but it might be enough to incriminate someone to get them on a suspect list (part of a record, one image…etc)

BTW, this is also how hackers find juicy bits of high-security stuff on peoples PCs – like credit card numbers, temp files or sensitive material.

Will de-fragging protect you from hackers? Maybe. Less slack space means less likelihood that your computer will decide to pack them out with deleted/dead files.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Something New Every Day – Lecture 14 – Computer forensics & digital evidence

Someone worked really, really hard to come up with the acronym for the USA Patriot Act. In fact there’s apparently a name for this practice of retro-fitting a great acronym – a ‘backronym’ (thanks Wikipedia)

The USA PATRIOT Act actually stands for Uniting and Strenghtening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism and it is the legislation enacted after the Sept 2001 attack on US sites to give Govt authorities much greater snoop-and-detect powers.

A sexy name for a whole bunch of covert intrusions. Not saying they’re not warranted or getting results but my money is on them having existed for a while and 911 was just a really opportune moment.

But as far as the backronym goes, I feel like it’s not their best work. Kind of daggy, no?

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Something New Every Day – Lecture 13 – Handwriting and forgery analysis

The TV cliché of a detective lightly rubbing a pencil on an indented document to read what was scrawled on the page above it would never be used in a real forensic situation. Doing that ruins the paper for fingerprinting or any further testing and can even smooth out the indentation and oblitirate the message.

Much better is to use an electrostatic device to recover indented writing. Document specialists place a thin plastic sheet on the document and slide it into an electrostatic box. The plastic is electrically charged and dusted with black toner which sticks to the plastic sheet and reveals the lettering as a ‘print’. This method leaves original unharmed for further or repeat testing.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Something New Every Day – Lecture 13 – Handwriting and forgery analysis

When investigators need to get an exemplar (a sample of their writing) from a suspect who might have a vested interest in disguising their handwriting, two methods are used simultaneously to reduce the ability of the suspect to fake/disguise their handwriting.

First, investigators DICTATE the phrase they want written because a suspect can’t concentrate fully on what (or rather how) they’re writing while they’re also listening).

Second, they disguise the words they want to compare in a longer passage with a different context. For example, say you wanted to see the phrase ‘Put all your til money in a bag, I’m armed’ because that’s what was in a real crime note handed to a bank teller… investigators might ask the suspect to write out:

“Don’t put all your pens and pencils away til we collect up money for the excursion in a bag. I’m serious. Then make sure the alarm system is armed.”

And third, they make you write it twenty to fifty times, potentially different statements, to make it harder still to keep up a pretence.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Something New Every Day – Lecture 12  Drugs and poisons

The hallucinigen d-lysergic acid diethylamide (LSD) derives from a fungus that grows on improperly stored grain. A dose as small as a full-stop/period of pure d-lysergic acid diethylamide can cause auditory and visual hallucinations that can last 12 hours. It is not addictive but can cause psychosis & flashbacks months or even years later. People try to disguise LSD for trafficking by liquefying it and soaking paper in it, selling it in tablets or building it into the gelatine casing of regular capsule based medications. It has been disguised on the back of postage stamps and in the adhesive strip on envelopes

Those poisoned though exposure to d-lysergic acid diethylamide from bread made from infected grain suffered ‘Saint Anthony’s Fire’, a condition marked by painful seizures, spasms, itching, mental psychosis/mania, headaches, nausea and vomiting/diarrhoea. This condition has been linked to the supposed cases of ‘bewitchment’ in the 1600’s that led to the Salem Witch Trials where the poor, infected people were determined by their symptoms to be bewitched and executed as witches.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Somethign New Every Day – Lecture 12 Drugs and poisons

Cocaine is extracted from the cocoa leaf via hydroclauric acid to make cocaine hydrocholoride (aka:  ‘snow’, ‘flake’, ‘blow’). 110 million pounds of cocoa leaves are produced in South America per year and the people at each end of the chain are the exploited ones while the men in the middle make all the money. A grower might get $250 for 500 pounds of cocoa leaves (.50c per pound). The manufacturers turn that into 1 pound of pure cocaine which they sell for $1000 (400% profit).  Traffickers dilute it with god knows what (to make it stretch to 5-pounds) and ask $25,000 for that (netting them a 2,500% profit with a product that’s only 20% cocaine). On the streets, dealers cut that 5-pounds down into one-pound lots, and sell them at around $150,000 per pound (300,000% profit). At every single stage the sellers cut it with whatever they can get away with and the street sellers flog it in one gram increments for whatever they can get for it (but around $600).

So, at one end of the production chain the sad, addicted user is paying $600/gram for horribly diluted and potentially deadly cocaine mixed with god knows what (the same weight of totally pure cocaine the manufacturers paid just $4 for) and at the start of the chain the growers get 0.0001c for the raw cocoa leaves.

*shakes head* No wonder it’s amongst the biggest industries in the world. And that’s just one drug.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Lecture 12 – Drugs and Poisons

More time and resources in crime labs is spent testing and investigating illegal substances than ALL OTHER evidence combined.

More than 50%. For this reason, the US Proceeds of Crime Act mandates that the $$ raised through selling the property of the criminals goes to the agency that caught them to specifically fund their chemistry lab.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Learn Something New Every Day - (Lecture 11) Mass Spectrometry

You see TV characters waving test results around and talking loudly about the mass spectrometer (a forensic machine-that-goes-ping) but have you ever looked up exactly what this is?

Without getting technical (please Lord don’t require that!), a bunch of smart people fire a laser through the gas that is created when a forensic sample is heated up and emulsified down, the resulting elements are weighed and their atomic charge is taken.

While someone wipes all the emulsified goo out of the machine, those elements are measured and assigned a ratio of MASS:CHARGE. That goes along the bottom of a chart and the quantity of the element in the sample is reflected in the STRENGTH of the spike for that element.

The resulting pattern of ‘ingredients’ (by mass, charge and strength) are a visual signature for a chemical looking like a series of spikes along an axis. A drug fingerprint, if you like. Toxicologists learn hundreds (even thousands) of these prints at a glance and are able to determine the exact makeup of any substance.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Learn Something New Every Day - (Lecture 11) Forensic Toxicology

A British nurse killed his pregnant wife by overdosing her on insulin and then putting her in the bath.

He had bragged to colleagues for years that insulin overdose would be the perfect way to commit murder because it is so quickly cleared from the body by metabolism. So he dosed her up and then (allegedly) put her in the bath unconscious where she subsequently drowned. But he made a series of mistakes including throwing her sweat-drenched pyjamas into the laundry hamper for investigators to find (the sweat subsequently tested SKY HIGH for insulin). He also injected her on the buttocks (which bruise easily and made the injection marks easier to find) and then put her in the bath. Had he left her in bed, the bruising from dying on her back (and therefore lying on her buttocks) might have disguised the injection marks.

But the big oops was that he seems to have completely forgotten that a dead body doesn’t metabolise, so all that insulin was preserved in her body like a time capsule instead of being purged into non-existence.

Dumbass. 

Double-murdering dumbass.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series

Learn Something New Every Day - (Lecture 11) Forensic Toxicology

Five things you possibly didn’t know about drugs and the body

1. Willow bark (the bark of Salix alba) contains naturally occurring salacin which is similar to the acetylsalicylic acid which is the active ingredient in Asparin. As such it reduces inflammation and fever and is good for pain relief.  It’s slower acting, but lasts longer.

2. When the 1982 Chicago tylonol poisonings happened in the US, 7 people died from Tylenol that had been injected with cyanide by a psycho who was never caught. Tragically, the family of the second victim held the wake at his home and his brother and sister both took tylonol from his cabinet for grief headaches and subsequently died. It was this case that led investigators to really look around at what was in his home and ultimately link all seven deaths to the poisoning.

3. Hair follicles are the tree rings of the body. Scientists can examine the hair and identify the changing chemistry of the body as it was playing out in the hair follicle over weeks and months. This makes hair excellent for gathering a chemical history on a victim or suspect.

4. Most people know that you can develop a TOLERANCE as your body adapts (or gets used to) a drug but did you know you can have REVERSE TOLERANCE (or ‘sensitisation’) where your body can get increased effects from the same dose of drug.

5. Chronic addicts can die from the too-sudden withdrawal of certain (heavy) drugs. So all those clinics slowly withdrawing people off drugs aren’t doing it as some kind of twelve step process, they’re literally saving the person’s life. Drug addiction (as distinct from drug dependence) creates a literal and physical need to continue functioning. The body cannot function if the thing is no longer present. So weaning is about creating a tolerance in the body for the ABSENCE of certain drugs.

‘Trails of Evidence: How Forensic Science Works” is a The Great Courses DVD lecture series