Ricin

It's a toxicology marathon this week, today we're looking at ricin. Ricin's rise to fame was catalysed by the assassination of Georgi Markov. Markov's mysterious death was discovered to be due to a pellet of ricin injected into his leg by a contraption in an umbrella. Ricin is especially deadly as it takes a comparatively long time to kill compared to the other poisons featured.

Name: Ricin

Structure: Glycoprotein

Effect on Victim: Ricin has serious effects but not ones immediately seen as life threatening. Ricin's symptoms include dizziness, a high temperature, vomiting and diarrhoea. However Ricin can cause death in just 24 hours. Ricin works by inhibiting the cell's ability to synthesis proteins from amino acids according to the mRNA received in the ribosomes. These proteins are essential and without them the body quickly dies.

Lethal Dose: The lethal dose is just 22 micrograms per kilogram if ricin is injected, however if it is taken orally the lethal dose is much higher, around 30 milligrams per kilogram.

This is a photomicrograph of the pellet found in Markov's leg. The pellet held less than 500mg of ricin, a testament to it's lethality!

Diagnosis: The symptoms are akin to a very severe, incredibly quick working septicaemia. Since much more ricin is required to kill orally than by injection any puncture wounds should arouse suspicion. Ricin can be made from castor oil, so large quantities of that is also a clue. Ricin can be identified by mass spectrometry in a sample of tissue so it can be detected in human tissue. This works by detection of selected marker peptides specific for ricin (Ricin is composed of two protein chains); T5, T7, T11, T12, and T13 from the A-chain and T3, T5, T14, T19, and T20 from the B-chain.

You may remember me warning you to steer clear of apricot kernels, due to the possibility of cyanide poisoning, well castor seeds are a very similar case. Thanks for reading, over and out!

Carbon Monoxide

Another addition to the poison's catalogue, this time in the form of one of the most feared gases around. Carbon monoxide is so notorious due to the fact it's not only easily produced but is a colourless, odourless gas. I'm going to go through how Carbon Monoxide works and how to diagnose a carbon monoxide poisoning.

Carbon Monoxide's not a gas to mess around with!

Name: Carbon Monoxide

Formula: CO

Effect on Victim: Carbon Monoxide's effects appear relatively tame compared to the other poisons I've covered. Acute poison monoxide poisoning doesn't cause any vomiting, hair loss, convulsions or paralysis. What Carbon Monoxide does is more subtle. Acute Carbon Monoxide poisoning results in a headache, followed by possible nausea, then dizziness, breathlessness. If the person hasn't managed to escape the poison by now they'll collapse and lose consciousness. Once this happens they'll soon die due to mass cell death. Carbon Monoxide works by preferentially binding to haemoglobin over oxygen. This means that the pp (partial pressure) of Oxygen becomes extremely low in the blood. This makes it extremely difficult for cells in the body to take up the oxygen from the blood which they need for respiration to produce ATP. Carbon Monoxide is commonly used in suicides as the loss of consciousness means it is relatively painless.

Lethal Dose: 0.16% concentration in air will kill in less than two hours, however a 1.28% concentration can kill in as little as 3 minutes.

Diagnosis: Carbon Monoxide has one very distinctive calling sign which will alert you immediately to poisoning. This is the rosy colour it induces in the victim. Carbon Monoxide poisoning causes a bright, cherry pink which persists long after death. This can be confirmed by a blood test to see the levels of CO in the blood. On average a Carbon Monoxide poisoning victim will have a CO% saturation of the haemoglobin of 60% . You must factor into your analysis that smokers already have a Carbon Monoxide blood level of around 8-12% . Women, children and old people will also general have a lower lethal level.

There's the quick guide to carbon monoxide. Hopefully after this you'll see the reason for the drive for everyone to fit Carbon Monoxide detectors. Just remember cherry coloured skin is bad news. Over and out, as ever any feedback is welcome, thanks for reading!

Thallium

We're back to toxicology today.Thallium has a short but extremely notorious history, Thallium is a scarily effective poison. Only discovered in the 18th century, thallium has become one of the most feared poisons.

Name: Thallium, usually used as a poison in the compound thallium (I) Sulphate

Chemical formula: Ti, usually Ti2SO4

Effect on Victim: Thallium is an extremely toxic element, it's shocking that it saw so much use in the cosmetics industry (a surprisingly common trait among poisons). Thallium (I) compounds are highly soluble so readily absorbed through the skin, even touching Thallium is dangerous. Thallium has been popular as a poison not only because it is so readily absorbed by the body due (due to it's similar structure to potassium which the body needs) but also because it is completely odourless and tasteless, it's undetectable by nose, eye or tongue in almost any drink. Once inside the body Thallium works similarly to serious pneumonia. Acute cyanide poisoning induces nausea, vomiting, shortness of breath and death after about 30 hours. Thallium however displays a far more distinctive symptom when administered in gradual doses, alopecia. Thallium is actually causes hair loss with amazing rapidity, which is why it was used in the cosmetics industry. Thallium actually kills by entering the cells in the place of potassium, through potassium-sodium pumps on the cell's surface. once in the cell, where potassium helps maintain fluid balance in the cell and and feeds nerve cells, thallium disrupts chemical reactions, destroying cells ability to function correctly. Thallium spreads so efficiently that this effect soon becomes body wide.

Lethal Dose: 15-20 mg/kg of body mass

Diagnosis: Thallium gets it's name from the trademark green it exhibits in both a flame test and a spectroscopy test. Suspicions should be aroused by the hair loss associated with Thallium. Confirming these suspicions requires only a spectroscope test of the tissue. Thallium will display a distinctive bright green line.

This is a uniquely bright and vivid green.

You acquire the sample for the test through quite a delicate chemical reaction:

1. Grind down sample of tissue

2. Add nitric acid in excess to the tissue in a flask and leave for an hour

3. Place the flask in a steam bath for 2 hours (until tissue has completely dissolved).

4. Cool and filter solution through glass wool. Place resultant solution over an open flam.

5. Carefully add Sulphuric Acid to the heated solution (acids are much more corrosive when hot).

6. Leave the resultant sludge-like solution to settle down and then slowly trickle nitric acid into it. You should observe this colour change:

 red -> yellow -> colourless

When the solution is completely colourless it is ready. 

There's your basic guide to the analysis of thallium. Thallium is potentially hard to detect due to how similar it is to pneumonia in some respects, however there are warning signs. Just remember to look out for green tinted urine in acute poisoning cases and hair loss in gradual ones. Once again thanks for reading and feel free to comment with suggestions, criticisms, ideas or opinions. Over and out!

Rough Guide to Forensic Entomology

This title may be more confusing to some of you, to be honest the first time I encountered the word 'entomology' was in the webcomic XKCD (which I 100% recommend to anyone with a healthy interest in any area of science). Entomology is the study of insects, and so forensic entomology is the study of insects in the context of criminal science. The most common application of entomology in forensics and the one which I'm going to be discussing in this article is determining how old a corpse is by the insects on or in it, but will also touch on the fact insects can be used to determine whether the body has been moved after death.

Forensic entomology is most useful on corpses which have been discovered soon after death. Knowing your insects and their life cycles is vital for this. Within minutes of death the body will be colonised by the true flies (Diptera), specifically flesh flies (Sacrophagidae) and blow flies (Calliphoridae). They lay egg and deposit larvae extremely quickly in the orifices of the corpse, or in the wounds. Blow flies are generally more useful to the forensic pathologist as they have more stages in their development, laying eggs whereas the flesh flies deposit live young on a corpse.

The life cycle of blow flies can be used to determine rough amount of time the corpse has been there, this is a relatively simple process for anyone with a knowledge of entomology as blowfly stages of development are pretty distinct:

Blow flies are surprisingly pretty insects

1. Eggs: Look for tiny, yellowish eggs. The presence of nothing but eggs shows that the corpse has been there for around 23 hours or less. 

2. Instar 1 : Small larvae, look for tiny (around 5mm) fleshy covered maggots. The presence of only extremely small larvae (and maybe eggs) will show the corpse has been there for 23 - 50. 

3. Instar 2 : Medium sized larvae, exactly the same as the instar 1 stage but significantly bigger (around 10mm). The presence of no larvae bigger than instar 2 larvae shows the corpse has been there for 50 - 77 hours. 

4. Instar 3: Anatomically exactly the same as instar 2 but significantly larger (around 15mm). The presence of instar 3 larvae but no pupa indicates the corpse is 77 - 207 hours old. 

The larvae look anatomically identical at any stage, it's the size that counts!

5. Pupa: More difficult to find and sometimes found not on but in the vicinity of the corpse. Pupa resemble small dark red husks. The presence of pupa indicates that the corpse 207 - 350 hours old.

Pupa are more difficult to find, especially around the corpse as they are often mistaken for animal droppings.

 After about two weeks (the end of the pupa stage) the copse will probably be stripped to skin, bone and cartilage and the flies will move on. Thus the presence of no blow flies in any stage of development shows that the corpse is older than two weeks. 

This is a very easy to apply method of estimating the age of a corpse however you must take into account environmental factors in your estimations. All of these time measurements are given for 23ºC , so higher temperatures will mean your times must be adjusted to be lower and colder will increase the length of time.

Insects also provide evidence of whether the body has been moved, for example the insects found in urban areas differ greatly from those found in rural areas. This difference can be used to find out for example if a body has been killed in a city and then dumped in a hedge in a rural area.

Forensic Entomology's uses even stretch to toxicology. corpses which have decayed to the point where they have lost most of the tissue are extremely difficult to test for poisons (almost all non-radio active poisons affect major internal organs, nerves and tissues but not the bones). However, as the larvae feed on the dead tissue (technical term is necrophagous) they mimic almost precisely the concentrations of toxins in the body of the human as they decayed, meaning a sample of larvae is a decent substitute for a toxicologist to analyse.

That concludes the quick guide, all in all entomology is as useful as you make, the more you learn about specific life cycles and geographical locations of specific insects will let you gather more, more accurate data on corpses. However with just this information you can make a quick estimate of how long a corpse has been there, a great trick for any aspiring detective.

Cyanides

Continuing with the poison 'all-star' series started by arsenic, in terms of homicidal popularity cyanide has to be a close contender.

Name: Cyanide (Hydrogen, Potassium and Sodium Cyanide are the most common forms)

Formula: HCn, KCn, NaCn

Effect on Victim: Cyanide is one of the most popular poisons seeing use not just in 'standard' homicides but also in even more horrendous circumstances such as in the Nazi gas chambers and even as far back as ancient Egyptian death sentences (where it was referred to as death by peach due to the fact it could be extracted from peach kernels). Cyanide kills by inhibiting the enzyme aa3, which is found in the mitochondria of eukaryotic cells. The blocking of this enzyme inhibits the cells ability to respire aerobically, which is especially deadly for the CNS (central nervous system) and heart. The effect of stopping cells from effectively respiring is known as histotoxic hypoxia. Histotoxic hypoxia rapidly leads to mass cell death and then complete death, usually within minutes. The gaseous cyanide, hydrogen cyanide, is especially deadly as inhaling only a very small amount will kill extremely rapidly. Cyanide deaths are quick but also extremely unpleasant. A victim of acute cyanide poison will quickly collapse, convulse and then gasp for air through a bloody, frothy vomit before succumbing to the poison and falling into a coma before dying. Not the way I'd want to go, its relatively widespread use in suicides really puzzles me.

Lethal Dose: Cyanide is very deadly, the gaseous form requiring a lethal dose of just 270 ppm in air (that's parts per million!) and the solid or aqueous forms only 200 mg of the stuff.

Diagnosis: Luckily, like arsenic, cyanide is relatively easy to detect. In fact most cyanide corpses are a text book study in violent death by poison. Straight off, before any post mortems are carried out, the corpse will be bruised and a discoloured bluish, hideously twisted by the convulsions involved in the death and if you're on the crime scene quickly enough the poison's trademark 'almond' scent will still be hanging in the air. Autopsying the corpse can prove suspicions of cyanide poisons beyond a doubt. First of all cyanide poisoning causes the blood to become a much darker red, in some cases even purple. There are many tests for cyanide in the body. One of the most popular is a test called the prussian blue test, pioneered by a toxicologist named Alexander Gettler. Take 200g of lung tissue and mince it into a paste and then break this paste down with a small amount of acid. Distill the resultant liquid in a steam bath and then condense it into a chilled flask. Now you are ready to perform the test:

1. Add 2ml of the solution to a test tube in the fume cupboard.
2. Add 2 drops of 10% ferrous sulphate and 3 drops of 10% sodium hydroxide solution.
3. Warm the mixture to 50ºC for 5 minutes.
4. Add one drop of 1% ferric chloride solution and then acidify the solution with a couple of drops of concentrated HCl.
5. A blue precipitate or colouration will display the presence of Cyanide in the tissue.

this is the blue you're looking for

And that's that, armed with these techniques identifying and proving a cyanide poisoning should be no problem for the adept chemist. On a side note beware of peach kernels (as I mentioned earlier), there have been more than a couple accidental deaths due to the arsenic levels in these. Over and out, thanks for reading.

Rough Guide To Blood-spatter Analysis

   This time around we're taking a short break from toxicology to explore a field of forensics many of you may know from the TV show series 'Dexter'. Given that the human body contains around 5 litres of blood, it shouldn't be surprising that not only are blood stains extremely common at crime scenes but also that various techniques can be applied to find out valuable information about the crime. There are 3 main types of bloodstain: active, passive and transfer bloodstains.

Active bloodstains are those made to travel by a force other than gravity. These can occur from the force of impact with a weapon like a baseball bat, more likely blunt weapons than blades. These impact blood stains will result in numerous droplets of blood covering the target surface. Active bloodstains may also be caused by the blood pressure shooting out of breached arteries in gushes (large amounts) or spurts (small amounts). Since the blood assumes a spherical shape in the air, on collision with a surface like a wall it will create a tear shape. This is incredibly useful information. The first thing it letss you determine in the direction of travel. 

As in this example, the tails clearly indicate the direction of blood splatter. As the angle at which the blood hits the surface becomes shallower the blood droplets' tail becomes shorter. by finding the completely circular blood drops you can find the trajectory and point of origin of the blood splatter. This is where maths, for the first time in my entire life is actually interesting. By using sin ratios and two blood droplets you can work out the location of their origin. Since we know blood travels through the air in a spherical shape, the width at the widest point of the stain equals the height of the sphere, this gives you the opposite in a triangle and the tail length is the adjacent so using trigonometry you can calculate the angle of the hypotenuse which will be the direction it flew,the equation for anybody finding the maths hard to follow is angle of impact = sin^-1(Width/Length). If you do this for two blood droplets and then use algebra to find the intersection point you know the distance they came from.

Passive bloodstains are those formed by gravity. This means blood flows pools and drops from the victim (no gushes or spurts). These are helpful as the flow patterns which look unusual are a clear indicator that the body has been moved after death. In addition passive blood stains may provide clues as to the length of time since bloodshed, by the analysis of drying times simply through observation of sample against a recreation (same amount of blood, same surface, same temperature etc.). Blood droplets form a circular crust within minutes of being exposed to air. This crust is very difficult to wipe away so the presence of these circles shows that some has attempted to clean up the blood. 

Transfer Stains are those which occur as a result of direct contact with the objects covered in wet blood. These stains are extremely common at any type of bloody crime scene and will often give valuable information as to the movements of any individual involved. This is a relatively intuitive process. Repeated marks will give away the movements of the individual, for example footprints will be strongest at the start of the trail and fade with each step until they must be traced using a reagent caused luminol. Whose blood it is must also be taken into consideration but DNA analysis is a topic for another day. 

Well there you go, you now know your way around a bloody crime scene. I feel these techniques prove why preservation of the crime scene is so important as smudging the blood, even slightly in some cases can make your analyses veer off. All that's required to piece together a violent crime is a well-preserved crime scene, some decent maths, a little common sense and possibly some luminol. Now you can get annoyed when TV detectives miss simple clues like these. Thanks for reading!

Arsenic

  Todays post is a fact file on the cheery substance that is arsenic.

Name: Arsenic, most commonly used in the compound Arsenic Trioxide or White Arsenic

Formula: As for arsenic, As2O3 for white arsenic. 

Effect on the Victim: Usually absorbed by mouth, the digestive system is where arsenic is at its most deadly however toxic effects can also be observed when inhaled or absorbed through skin. Arsenic poisoning usually involves digestive problems and the body desperately trying to get rid of the poison. This involves acute abdominal pains, vomiting and usually bloody diarrhea. It may also cause cardiovascular problems, liver damage and convulsions. Arsenic is an enzyme inhibitor and which causes death through organ failure, and also a possible narcotic as it has been theorised it has a narcotic effect on the cells it kills as they do not have enough energy to kill themselves (through apoptosis), 

Lethal dose: Arsenic has an extremely small lethal dose of as little as 0.15gm for a 73Kg healthy male adult. 

Diagnosis: Arsenic only requires an extremely small dose to prove fatal, is relatively is easy to acquire (white arsenic is still used in some fertilisers) and when mixed into food or drink (especially alcohol) is almost impossible to taste, see or smell. It is for these reasons that Arsenic has been one of the most popular homicidal poisons over the ages (famously by the 15th century political assassins Cesare and Lucretia Borgia). Fortunately despite the method of death resembling many natural causes it is relatively easy to detect Arsenic poisoning in a corpse. The first factor which should alert you to Arsenic poisoning is 'arsenic mummification'. Arsenic creates unusually well preserved corpses. Many arsenic victim's corpses do not decompose for months after burial (with the exception of mould growth which is unaffected). Upon dissecting the corpse the bloody work of arsenic is quickly apparent. Death by arsenic destroys the stomach, covering it in bloody lesions and the membrane lining will be extremely swollen and off-yellow with scarlet patches. The actual white arsenic is easily observable under a microscope as the tissue where it builds up (mainly the stomach but almost everywhere else in the body, especially in larger than necessary doses) will sparkle due to the tiny crystals.

That's all the information needed to diagnose an arsenic death.  If you want to deduce it without the need for operation Sherlock style the key points to look for are:

 1. Had the victim or patient been drinking or eating just before they died.

 2. Did they seem to die from a severe digestive problem (lots of vomiting and diarrhea)

 3. How well is the corpse preserved?

Here's a practice case:

  Six New York office workers have been found dead. They had collapsed on the floors of their offices at around 14:30. They convulsed and vomited until death. All six of the office workers had had lunch at the same place and all six had had the same dessert. The victims corpses have been eerily well preserved. Autopsy has revealed severe damage to the stomach and sparkling tissue.

Okay well this is an easy one. By the time you hear that all six have eaten the same thing and collapsed vomiting shortly afterwards you can guess it's arsenic. The mummification and sparkling tissue as well as stomach damage confirm this. Bonus points to anyone who deduced that the arsenic must have been added to a specific dough and therefore was not a mistake as only six people died and only one type of food from the restaurant linked them. 

Thanks for reading, I'll get the next post up soon. Feel free to comment with any suggestions!

An Introduction to Poisons

Before you can even begin to look at how certain poisons affect the body and what the tell tale signs of them are the obvious is question is what are poisons and how do they work. The first thing to do here is to define what we mean by a poison. the dictionary definition of poison is:

"A substance that when introduced into or absorbed by a living organism causes illness or death."

That sums up what poisons are used for but there is a major flaw in this definition of poison. Anything in absorbed or introduced in a great enough quantity will cause illness or death to a living organism. I'm not just talking about drugs but everything from the air we breath (there have been documented cases of CO2 poisoning for example) to food that we eat (obesity and diabetes are both food based illnesses which may result in death). Thus I think a better definition would be the definition put forward by Andrew and Julie Jackson in their textbook, imaginatively titled forensic science:

"A poison is any substance  that produces an injurious or lethal effect when administered to, or otherwise taken up by an organism in too high a quantity".

This definition nicely acknowledges the fact that basically anything can be a poison if you ram enough of it into the victim, however this still runs into the problem of everything being a poison, which isn't helpful in a legal environment. Thus we need to put a number to how little of a substance must be deadly to qualify as a poison. The number used by the United States and the number which will be used in the rest of this blog is 50mgkg^-1of body weight or less. This means just 3/4 of a teaspoon would be enough to kill an average man. Now that's out the way we can get to the really interesting stuff. The types of poison I will be looking at I'm going to organise into groups based on how they attack and damage the body. This grouping system will make it easier to identify common traits between poisons and by extension common effects of these poisons on the body.

1. Enzyme Inhibitors: Enzyme inhibitors kill by slowing down enzymes through various means. When enzymes are slowed down the body loses the ability to properly carry out certain reactions. Within minutes this can lead to a wide range of equally unfortunate problems from liver failure to muscular paralysis depending on the enzyme blocked. Enzyme inhibitors cause rapid death and a lot of them are fairly easy to obtain which is why they are some of the most common poisons used in murders. Examples of enzyme inhibiting poisons are cyanide and deadly nightshade.

2. Nerve Agents: Nerve agents are among the most dangerous and gruesome poisons out there. The fact they are classified as a weapon of mass destruction by the U.S. is a testament to their lethality. Unsurprisingly nerve agents attack the nervous system of the human body, normally by blocking the receptors of the stream of sodium ions which is how the body communicates through nerves, however there are a variety of imaginative ways these substances interfere with the human body. The status of these poisons as weapons of mass destruction means a forensic pathologist will very rarely encounter them as obtaining them is practically impossible. Examples of nerve agents include the notorious sarin and tabun.

3. Corrosive Poisons: Corrosive substances are ones which damage other substances they come into contact with, usually causing chemical burns if the substance is organic. Corrosives are particularly dangerous as their effects are instantaneous, whereas other poisons kill over a longer time period giving more chance for a medical 'intervention'. Acid -base reactions are how corrosives break down organic tissue they come into contact with (amide and ester hydrolysis). Corrosives are usually acids or bases such as sulphuric acid or bleach.

4. Narcotics: Technically a just a substance with sleep inducing properties, narcotics account for a surprisingly large number of drug related deaths, primarily just due to how many narcotics there are. Narcotics often become deadly when they also fall under one of the other categories of poison. Narcotics are also especially linked to 'accidental' deaths or deaths linked to misuse of drugs, since carbon monoxide, heroine, chloroform and morphine are all narcotics.

These four categories, especially when used in conjunction cover every poison a forensic pathologist is likely to encounter. Knowing how these poisons work is a vital step in analysing them. For example a victim with no external injuries who is found to have died by asphyxiation, in their sleep with a rosy pink tint to the corpse immediately leads to a diagnosis of carbon monoxide. The fact they were asphyxiated points to a nerve poison, the fact they dies in their sleep points to it also being a narcotic and the rosy tint left on the corpse is a specific symptom of Carbon Monoxide. I aim to use these categories to help with my more in depth analyses of specific poisons. I will also dedicate at least one article to each of the categories, exploring in depth the chemistry behind each one. Stay tuned, I'll report in soon!

Introducing my handbook

   Hello and welcome to what I intend to be a compilation of everything I learn to do with the field of forensics and art of deducing how murders happen. Hopefully by the end of this I'll be a fully functioning Sherlock Holmes. Here's how I'm going about it.

   The plan:

1. The hard work; I'm going to juggle my academic work and my extracurricular reading. Don't worry though, I'm fully committed to this blog. Researching the various techniques employed by forensic pathologists is my hobby and I'm always keeping a couple of books on the go. Each week I'll do in depth research into a particular aspect of forensics and toxicology. I'm going to be doing a lot of close studies and fact files for specific poisons but fear not, I'll also branch out to include other things which tickle my fancy (for example blood spatter analysis or identifying corpse age by insect life on/around it). This should build up into a comprehensive index of useful and interesting techniques.

2. The fun part; I'll take time at least once a week to write up my research into an article on this blog for you to enjoy. The articles will vary in length but I'll keep them to a good academic standard. This means good old, no bullshit, references included, hard chemistry, biology and maths (physics isn't my strong suit unfortunately).

  So strap in and enjoy. I hope anybody with a healthy interest in forensics from crime scene, csi show fans to students with a wide ranging interest. The first post will be up soon and we'll be kicking off with a quick guide to types of poisons.

P.S. If there's something you want me to ook into just leave a comment and I'll see what I can do.