PDA

View Full Version : Toxicology tests, how do they work?



Foolonthehill
11-07-2013, 07:22 PM
I need the lawyer of my main character to want to carry out a toxicology test to find out how much and what kind of drugs his client was on when a certain crime was committed? Could he do that by using a piece a sample of hair that was taken from the client on the day he was arrested? If so, would he be able to determine, more or less, the amount and kinds of drugs? How would a lawyer be able to get his hands on said piece of hair? Thanks!

Haggis
11-07-2013, 07:40 PM
I need the lawyer of my main character to want to carry out a toxicology test to find out how much and what kind of drugs his client was on when a certain crime was committed? Could he do that by using a piece a sample of hair that was taken from the client on the day he was arrested? If so, would he be able to determine, more or less, the amount and kinds of drugs? How would a lawyer be able to get his hands on said piece of hair? Thanks!
That's not going to work for you Foolonthehill.

First off, you're going to need much more hair--alltogether about the thickness of a pencil. And it's going to have to be collected under strict chain of custody protocol. If the test comes back positive it will tell you what drug the individual has ingested (or at least the general type of drug--i.e. it could be positive for Morphine, an Opiate, but the individual might have used Heroin).

You're also not going to be able to determine if the individual was under the influence of the drug at the time the hair was collected. Hair has a detection window of up to 90 days--much longer than the effect of the drug itself.

Foolonthehill
11-07-2013, 08:50 PM
Oh, but you just gave me a solution, then. I could have the lawyer carry out the toxicology test on a sample of hair he takes from his client after the crime, which in my novel has only taken place about a week before and the toxicology test would show how much drugs and which kinds he was on?

Haggis
11-07-2013, 08:56 PM
Oh, but you just gave me a solution, then. I could have the lawyer carry out the toxicology test on a sample of hair he takes from his client after the crime, which in my novel has only taken place about a week before and the toxicology test would show how much drugs and which kinds he was on?
The test will show the drug(s) taken over the course of the preceding 90 days. It will not necessarily show what drug he was "on" at the time of the crime. Also, of course, not all drugs are tested for. Is there a specific drug your character is supposed to have taken?

cornflake
11-07-2013, 10:10 PM
Oh, but you just gave me a solution, then. I could have the lawyer carry out the toxicology test on a sample of hair he takes from his client after the crime, which in my novel has only taken place about a week before and the toxicology test would show how much drugs and which kinds he was on?

I have to ask - why in the world does the guy's own lawyer want to know that?

Nothing the lawyer does significantly after the fact can find out what someone was taking at a specific time beforehand, regardless.

jclarkdawe
11-07-2013, 11:16 PM
Toxicology tests record the remaining life of a specific drug. Drugs leave the body at a constant rate or in half-lives.

So let's say I've got a toxicology test that shows a blood/alcohol level of 0.06%. Now if this was taken at 6 AM and the defendant says the last time he was drinking was Buggy Barn Bar, which closes at 1 AM, I can then back calculate and determine he was over the legal limit, as alcohol leaves the body at a rate of 0.015% per hour. This would give him a blood alcohol lever at 1 AM of somewhere around .12%.

Problem is how can I prove when he took his last drink?

As defense counsel in the US, I put the defendant on the stand, and he testifies that he was blitzed because he was taking whatever. I then put on an expert, who testifies that based upon what the defendant told him, it looks like he was on whatever, with an approximate dosage of however much.

If drug negates the offense (usually doesn't), then all I've got to do is raise a reasonable doubt that my client did it because of the drugs. It's up to the prosecution that despite what my client says on the stand, the drug did not negate the offense.

I don't want an exact number. I don't know what the number is going to show. And the only way I'm going to be able to do the chain of custody is if a doctor or nurse takes the sample. I can't get up on the witness stand to testify how I got some hairs, which is also going to probably violate a whole raft of jail regulations.

Best of luck,

Jim Clark-Dawe

Foolonthehill
11-07-2013, 11:19 PM
Let me explain. My guy (main character) is an ex drug addict who has been charged with murder (a murder he did not commit). When he was arrested he was high on a concoction of drugs as though he had relapsed, he had not had any drugs whatsoever over the previous six years or after the presumed murder (in fact, it will later turn out that he was injected with the drugs by someone else who wanted to make it seem like he had relapsed). The lawyer is not sure the toxicology tests were accurate (we're in Italy, things are not done like in the States here and if the police think someone is guilty, especially if they're junkies, they might be very negligent about certain things). The lawyer wants to prove certain things through the toxicology tests. In a nutshell. So he was only on drugs ONCE in six years, on the day of the crime.

King Neptune
11-08-2013, 12:46 AM
That he had not taken drugs until a certain time probably could be determined from the hair, as you suggested. If the sample was taken promptly, and it was found that no junk had been taken , except in the last little bit of hair next to the scalp, if that part of the hair had even come up. You, or someone else, will have to determine what drugs, because I don't think that all drugs end up leaving samples in the hair.

GeorgeK
11-08-2013, 12:47 AM
Let me explain. My guy (main character) is an ex drug addict who has been charged with murder (a murder he did not commit). When he was arrested he was high on a concoction of drugs as though he had relapsed, he had not had any drugs whatsoever over the previous six years or after the presumed murder (in fact, it will later turn out that he was injected with the drugs by someone else who wanted to make it seem like he had relapsed). The lawyer is not sure the toxicology tests were accurate (we're in Italy, things are not done like in the States here and if the police think someone is guilty, especially if they're junkies, they might be very negligent about certain things). The lawyer wants to prove certain things through the toxicology tests. In a nutshell. So he was only on drugs ONCE in six years, on the day of the crime.
This sort of reminds me of the French Connection. I'm not familiar with Italian forensics but I'm sure that they are on par with or close to current science.

Basically your scenario won't work. For you to say that someone was on drug X on Day Y, you will need an appropriate sample from Day Y such as blood, urine, cerebrospinal fluid, vitreus humor, whatever is appropriate for testing for drug X. Hair realistically won't work. (if this was the future and they actually do microslices and actually know how fast the hair grew as opposed to using averages, assuming it was a drug that actually got deposited in hair, then maybe in the future but AFAIK we are nowhere near that point, plus there's the whole chain of custody thing for evidence)

Maybe he donated plasma on the fateful day?

veinglory
11-08-2013, 12:58 AM
I doubt a one day period of use would be detectable in hair even for drugs that are deposited in hair (which is not all of them).

jclarkdawe
11-08-2013, 01:16 AM
Problem one is that being under the influence is not a defense against murder, other then in regards to the degree. In other words, you usually can't commit first degree murder while under the influence. But you can commit second degree murder usually while under the influence.

Problem two is that any testing for toxicology for criminal procedures involve taking a sufficient sampling so that you can run two tests. So the Italians take some blood to test him, and the defense doubts they did it right (which does happen). Defense requests second sample and then tests it. If the police failed to provide a sample, the Italian courts are very likely to throw the case out.

Problem three is that the government took blood or urine, a much better way of testing then hair.

Problem four is there's no way to tell from the test he had been clean for any period. You attempt to prove this through things like his sponsor. It's hard to do. And even if you prove the guy has been clean, it doesn't mean he didn't relapse that night.

There's a lot of information out there from the Amanda Knox case on Italian drug testing and how it works in their courts. What you're proposing doesn't match anything that sounds like Italian courts do. Where I see as the big difference between Italian courts and American courts on testing is that the experts testify to prove the prosecution's case, while experts in the US usually testify as to the facts, and if it tanks the prosecution's case, then it sucks to be the prosecution.

The DNA they're pulling off of the knife is degraded and an exceptionally small sample size. But their ability to pull even this DNA is pretty expert. Not that many labs in the US could have done any better. Where the Italian expert failed was in trying to make sure the facts matched the prosecution's theory of the case. This should have been qualified when the prosecution's expert testified, but was not.

Best of luck,

Jim Clark-Dawe

WeaselFire
11-08-2013, 01:16 AM
So he was only on drugs ONCE in six years, on the day of the crime.
Toxicology can't prove that. If he were tested daily for six years, you'd have the pattern you are looking for, but not in a single test administered after the day in question. And certainly not with hair.

In Italy, things change even more. You don't have the parole system to check with, and you don't have a great average for drug cases.

An option might be that he's allergic to one of the toxins in the mix and develops symptoms 48 hours after the incident. Allergies might be easier to prove and the lawyer may have an indication that he wouldn't have knowingly taken a mixture with something he's allergic to.

Jeff

Foolonthehill
11-08-2013, 08:22 PM
Weasle, what a wonderful idea! The allergy could come in really useful. It doens't have to be a hair sample, urine or blood could work too, cause the guy was arrested on the day of the murder, so the police could have got him to give a sample of urine. Still I wonder, would the lawyer be able to run further tests on the sample of urine the police took?
JClark, I had no idea Italian foreniscs were so up to date. I know there's a general and "comandante" of the RIS (forensic police) who is called Luciano Garofano who is considered a real expert in the field. Think he worked on the Knox case too.
Thanks guys, you're amazing!

jclarkdawe
11-08-2013, 10:21 PM
You need to understand that the toxicology tests you're planning on running would start out in the same way as they do in bicycle racing and soccer, both of which are heavily tested in Europe and it's a constant process. Although I don't think there's much difference at the top, I'd have to say that the French and Swiss labs seem to be at the top of their game, with the US behind them.

The US tends to do sports testing in private labs, rather then state labs. Most of Europe does it in state labs, with little use of private labs. There's two aspects of testing: protocols and ability to determine results. You hear about the protocol constantly, and you automatically start thinking two samples, so the protocol is pretty good. There's been some big scandals in sports over the past few years where one sample was dirty, and no second sample, and the athelete getting away with it because of that.

Lance Armstrong, among others, has greatly contributed to the improved quality of toxicology tests for drug use. But one of the things Lance Armstrong shows is that you have to have some idea of what to test for. If the drug is something that is normally tested for, I would expect the Italian labs to pick it up. If the drug is an exotic and not commonly known, then it's hit or miss, regardless of where you are.

Mistakes happen. Bad labs exist. (See the Massachusetts problems.) But for the norm, mistakes aren't very common.

Best of luck,

Jim Clark-Dawe