Forensic Science Questions

[kyuuketsuki]

Alright everyone... This is a forum revolving around detective work and crime. So this brings up questions about the methodology as well as the concepts of Forensic Science field.

Now I don't pretend to be an expert as I am still a student, but I have a decent knowledge as well as the means to find out more than the average person. Just so you know... if you have a question about something related to Toxicology, I likely won't be able to answer it right away, because my concentration is in Criminalistics and Molecular Biology. I should be getting my degree in the former by the end of next year if all goes well.

Just to quickly explain the different areas of concentration... Criminalistics is basically the study of trace evidence. THIS DOES NOT MEAN IT IS ALL ABOUT MURDER! All events have trace evidence, and Criminalistics is the study of that. Molecular Biology is... well more or less what it sounds like... It is the study of Molecules and Biology for the use in matters of law. What that means is that a Criminalist is likely to look at footprints, hair, fingerprints, blood spatter and so fourth... A Toxicologist will analyze a person's blood to find toxins or drugs. A Molecular Biologist tends to work with DNA and things of that sort.

So basically this topic is for your questions that I will answer about forensic science. This includes evidence, procedure and how things are analyzed. It could be of the real world or things that you want to know would be true in the case of Detective Conan or not.

I will likely be unable to answer questions immediately, because I do have both work and school... However I'll do my best to answer any questions you guys throw at me quickly and accurately... With any luck, things will be learned and the tyranny of CSI will end!

So what ever anyone wants to ask, go for it!


Links to the Question/Answer

How long does DNA analysis take?  Schillok addendum
Potassium Cyanide and other poisons

Links of interest

The Innocence Project A project dedicated to clearing the names of those people wrongly convicted by using DNA analysis and testing it with modern methods and techniques.
World of Forensic Science
Lockpicking Forensics
Not quite forensics but someone might like it: Theatre effects
Chemical pricing
FBI's list of methods of murder

[Edogawa4869]

Alright, here's the first question.  Taking away the CSI Effect, how long does DNA testing and things like that really take?

[kyuuketsuki]

Alright, here's the first question.  Taking away the CSI Effect, how long does DNA testing and things like that really take?

That really depends on a few things... First thing is the case's priority... In a DNA lab, a person is usually working on several different DNA samples at a time. Second is where is the DNA coming from? Working with a small amount of DNA takes a lot longer to test than say a source that is plentiful. Unfortunately for most forensic science, the source is usually very small.

The BARE MINIMUM amount of time needed is 5 days...

5 Days is assuming that you have a good sample (little to no recombination is necessary, which is basically duplicating the DNA so you can test it... When you test DNA you destroy it). In reality... a high profile case usually gets done in about... 2 weeks... At least that is the shortest period I have heard it took. DNA labs are horribly.... horribly backed up almost always. So for most cases it can take weeks if not months to get done...

PS: if you want to look up something interesting regarding DNA testing that is ongoing... Look up the Innocence Project. One of my professors has worked on it, and its goal is to clear wrongly convicted people by analyzing DNA evidence using techniques that were not available at the time of their conviction.

[Edogawa4869]

Alright, here's the first question.  Taking away the CSI Effect, how long does DNA testing and things like that really take?

That really depends on a few things... First thing is the case's priority... In a DNA lab, a person is usually working on several different DNA samples at a time. Second is where is the DNA coming from? Working with a small amount of DNA takes a lot longer to test than say a source that is plentiful. Unfortunately for most forensic science, the source is usually very small.

The BARE MINIMUM amount of time needed is 5 days...

5 Days is assuming that you have a good sample (little to no recombination is necessary, which is basically duplicating the DNA so you can test it... When you test DNA you destroy it). In reality... a high profile case usually gets done in about... 2 weeks... At least that is the shortest period I have heard it took. DNA labs are horribly.... horribly backed up almost always. So for most cases it can take weeks if not months to get done...

PS: if you want to look up something interesting regarding DNA testing that is ongoing... Look up the Innocence Project. One of my professors has worked on it, and its goal is to clear wrongly convicted people by analyzing DNA evidence using techniques that were not available at the time of their conviction.

Wow, CSI seriously exaggerates the speed of these processes!  I guess that's just the lure of ratings.  Thanks!

[Chekhov MacGuffin]

I have links to add to this topic.
World of Forensic Science
Lockpicking Forensics
Not quite forensics but someone might like it: Theatre effects

[Schillok]

Alright, here's the first question.  Taking away the CSI Effect, how long does DNA testing and things like that really take?

That really depends on a few things... First thing is the case's priority... In a DNA lab, a person is usually working on several different DNA samples at a time. Second is where is the DNA coming from? Working with a small amount of DNA takes a lot longer to test than say a source that is plentiful. Unfortunately for most forensic science, the source is usually very small.

The BARE MINIMUM amount of time needed is 5 days...

5 Days is assuming that you have a good sample (little to no recombination is necessary, which is basically duplicating the DNA so you can test it... When you test DNA you destroy it). In reality... a high profile case usually gets done in about... 2 weeks... At least that is the shortest period I have heard it took. DNA labs are horribly.... horribly backed up almost always. So for most cases it can take weeks if not months to get done...

PS: if you want to look up something interesting regarding DNA testing that is ongoing... Look up the Innocence Project. One of my professors has worked on it, and its goal is to clear wrongly convicted people by analyzing DNA evidence using techniques that were not available at the time of their conviction.

Wow, CSI seriously exaggerates the speed of these processes!  I guess that's just the lure of ratings.  Thanks!

But as it was mentioned the long time is mainly due to concerns about the scarcity of the sample, bureaucratic proceeding or insufficient number of lab workers.
In theory a DNA testing could be much faster.

DNA isolation: about 2 hours
PCR preparation: about 1 hour
PCR running: 2 hours
Preparation Capilary Gelelectrophoresis: 1 hour
Gelelectrophoresis: 1 hour
Analyze and Comparison: 1 hour


This is of course assuming that the tests for the different Short Tandem Repeats (STR) are carried out in parallel.
But it COULD be done in a single day if needed.

IIRC Saddam Husseins DNA verification after his capture (to check if he was not one of his many doppelgaengers) was completed within a few hours.
Of course the US army had the reference DNA profile at that time already, though. And they could have gotten another sample from the captured dictator if something went wrong.

[nomemory]

This is interesting, I don't have any questions yet but if something comes to mind I will ask

I take everything in CSI, and for that matter most TV-shows, with a big scope of salt.

[Crap4869]

This is interesting, I don't have any questions yet but if something comes to mind I will ask

I take everything in CSI, and for that matter most TV-shows, with a big scope of salt.

Same as above, I'll ask when I have a question. A great thread there, fitting for one in Detective Conan forum 

[kyuuketsuki]

@Schillok: That is only in theory... The rarity of that is high. I did not hear about the length of time it took Saddam Hussein's DNA testing, but I highly doubt it took only a few hours.

And yes... IN THEORY that is the length of time each step takes, in perfect conditions. That is however never the case.

[Schillok]

I wouldn't say never. Actually, these times are pretty accurate.

I did most of these step myself before, and the times were not much different from the numbers I gave here. With a bit more training 8 hours are more than enough.

As I said, this is for the method itself. I am just a Molecular Biologist, I don't know about criminologistics and all regulations involved. But if anything delays the DNA testing for days, it is not the fault of the scientist/lab/method itself.
(Obviously I used non-human tissue samples, but the method would be the same. Maybe a bit more sterile until the PCR to avoid contamination of the sample from the scientist, but that should hardly add additional time.)

[kyuuketsuki]

I wouldn't say never. Actually, these times are pretty accurate.

I did most of these step myself before, and the times were not much different from the numbers I gave here. With a bit more training 8 hours are more than enough.

As I said, this is for the method itself. I am just a Molecular Biologist, I don't know about criminologistics and all regulations involved. But if anything delays the DNA testing for days, it is not the fault of the scientist/lab/method itself.
(Obviously I used non-human tissue samples, but the method would be the same. Maybe a bit more sterile until the PCR to avoid contamination of the sample from the scientist, but that should hardly add additional time.)

I say never because I know the BS and what not that goes along with it... Yes the times ARE accurate... But not in a forensics setting. Which is why I say never... Bureaucracy sucks. I can tell you so many things that I hate about forensic science that has nothing to do with the science that I like...

[Kleene Onigiri]

I'd have a question o/

Well, not sure if it fits or if you can answer it D:
But in DC the poison usually used is Potassium cyanide. But I heard that this isn't the best poison to use, since you can track it easily for example. Is it also used a lot in real crimes (in case someone was poisoned) or not then?

[Chekhov MacGuffin]

I'd have a question o/

Well, not sure if it fits or if you can answer it D:
But in DC the poison usually used is Potassium cyanide. But I heard that this isn't the best poison to use, since you can track it easily for example. Is it also used a lot in real crimes (in case someone was poisoned) or not then?

Googling for "cyanide" and "murder" suggests yes. I am surprised to hear it is easily trackable. (I'm thinking chemically trackable like cyanide A produced by Sigma Aldrich has x contaminants and ratio isotopes.) Maybe if you have some powder left over, but after it's been ingested?

[Akonyl]

I'd have a question o/

Well, not sure if it fits or if you can answer it D:
But in DC the poison usually used is Potassium cyanide. But I heard that this isn't the best poison to use, since you can track it easily for example. Is it also used a lot in real crimes (in case someone was poisoned) or not then?

Googling for "cyanide" and "murder" suggests yes. I am surprised to hear it is easily trackable. (I'm thinking chemically trackable like cyanide A produced by Sigma Aldrich has x contaminants and ratio isotopes.) Maybe if you have some powder left over, but after it's been ingested?

I'd imagine it'd also just be one of those things where if you buy potassium cyanide, red flags go off and your information is holed off somewhere because it's one of those things normal people don't usually buy.

[Schillok]

I'd have a question o/

Well, not sure if it fits or if you can answer it D:
But in DC the poison usually used is Potassium cyanide. But I heard that this isn't the best poison to use, since you can track it easily for example. Is it also used a lot in real crimes (in case someone was poisoned) or not then?

Googling for "cyanide" and "murder" suggests yes. I am surprised to hear it is easily trackable. (I'm thinking chemically trackable like cyanide A produced by Sigma Aldrich has x contaminants and ratio isotopes.) Maybe if you have some powder left over, but after it's been ingested?

I'd imagine it'd also just be one of those things where if you buy potassium cyanide, red flags go off and your information is holed off somewhere because it's one of those things normal people don't usually buy.

I think you are overestimating things...

When I see how many poisonous substances most labs have - and if I consider how many labs exist - there should be a lot more people buying such substances than you might imagine. Though, at least for university they are organized by a central department that handles most of the orders of all lab groups. Maybe it might be slightly different if you tried to order such substances in a pharmacy, though.