DNA vs. Fingerprints

Depends on the state, but in general no. Not if they've gone to the forensics lab. There is a nationwide shortage for fingerprint analysts so they can end up with quite the backlog. However, if the state has full staffing for fingerprints and not DNA then they may be faster. DNA uses more instrumentation, but there tend to be more samples in general while fingerprints are labor intensive. In any case plan on 6-8 week turn around time. In serious cases attorneys may put a rush on samples. When I was with a lab, murder cases (or high profile perpetrators) tended to get pulled out of order. Everything else was analyzed as received. Here are some numbers for you: http://www.cga.ct.gov/2010/rpt/2010-R-0086.htm

Remember also that you have to have something to compare to the DNA/fingerprints. You can't force someone to give up their fingerprints in order to match them to a suspect.

Having said that - it's not difficult to explain how someone's fingerprints are in the database. In addition to getting fingerprinted anytime you are arrested, if you've ever been fingerprinted for a background check, you'll be in the system. So if you've ever worked in education, health care, commercial trucking, law enforcement, government, banking, military (just to name a few!!!) you'll have been fingerprinted for a background check.

DNA would be harder to explain. I think the only reasons to have your DNA in the system would be military or a previous criminal record. (Others on this board are welcome to correct me on this.)

Fingerprint ID is a quick electronic check now, provided the prints are in the system already. If someone has been printed in the last few years, it's almost a given that they are in electronic form and quickly available. Keep in mind that most people are never fingerprinted though, so there's nothing to check against.

There other part to this though is what you need for your story to work. Explain the circumstances and maybe we can suggest a way to write it.

Jeff

apgambrell said:

I was just looking for a way to speed up my story since DNA testing takes a long time. What is the fastest DNA can come back in a lab that isn't swamped?

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It would take a couple of days in the lab at a minimum. Even if that was all they were doing, there would have to be time for some reactions to take place, and there are two major steps that need some time between them.

This article describes how it is done.
http://seqcore.brcf.med.umich.edu/doc/educ/dnapr/sequencing.html

Search and you may find more of the details. I recently emailed an old friend about having ny DNA sequended, but she hasn't gotten back to me.

As a forensic toxicologist, please don't CSI your MS. I really hate that. Don't ignore the realities of forensics unless it's a sci-fi novel, then you can make the technology whatever you want.

If you want the sample processed quickly then you have to make the case high-profile and have a politician pull some strings to bring the sample out of the queue. Otherwise it sits in the queue until the analyst gets to it.

I guess I don't understand if this is sci-fi or not. If you're in a Utopian area where no murders have occurred then yeah it would be high priority and moved ahead in the queue at the urging of a politician or appointee. The other question is what are they comparing the DNA or fingerprints to? Do they have a suspect in custody or are you writing that the person who committed the crime already has a criminal record to match in the system? If it's sci-fi then you can write that everyone's DNA is already on file, but that's not the case in the real world. Also where are they getting the sample to test from?

Well here's some interesting stuff about Texas: https://www.texastribune.org/2013/08/18/prosecutors-worry-new-law-will-create-more-dna-del/

"In some Texas counties, it takes six months or longer to get DNA test results from the Department of Public Safety, says William Lee Hon, the Polk County criminal district attorney."

Here's the thing that I think gets lost a lot. DNA analysis is used in prosecution as further evidence against the suspect. In order to get a sample from your suspect you're going to have to have a warrant. In order to get a warrant you're going to have to show all the other info about why this is your guy.

Yes, a sample could get pushed through but since the sample won't help you catch the guy, it's not really high priority, know what I mean? If the murderer is a safety risk (serial killer on the loose!) then the priority will be catching the guy and rushing DNA for something you don't even have a match for is not going to help you do that although maybe they hope that it will match someone and you can justify a rush that way.

Here is a way for it to be plausible. The murderer is in custody but about to be released for lack of evidence. In that case you can hope that it will get rushed through. Maybe the cop is friends with the DNA analyst. Or maybe the cop is friends with someone with some power who can ask them to rush it.

You have to remember that the Lab will be processing thousands of samples from all over the place. When you work in the lab you don't even tend to know the details of the case, it's "here is sample 14DX-1253 analyze it and report it."

Also, I should point out that the samples collected from the truck would be in the queue, so small department using the numbers for Texas above they wouldn't even know the samples didn't match for 6 months. Then once they get permission to get the DNA sample from the suspect that would be subject to another long wait.

My vote is go for the good old fashion detective work.

apgambrell said:

My MCs have investigated the crap out of it and all signs point to the guy they have in custody: Possession of the truck the evidence was found in, the DNA of the victim, the suspect acting suspicious when questioned. In that case, would the suspects DNA even be necessary?

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Depends.

Theoretically, how would the DNA help the prosecution?

If it is his trunk, his DNA and prints are going to be all over it anyway. In that case having the suspects DNA (and prints) won't help much in that there is a logical reason for them to be there. However, if the victim's DNA or prints are in the truck, that places the victim in trunk, which may be important.

If it's NOT the suspect's truck, (stolen truck or something) than finding his DNA and/or prints might be important. Again, it depends, if he was captured in the truck, than they already can place him in the truck as far as evidence goes and don't need to confirm that with the suspect's DNA.

Now, if you find the suspect's DNA in the victim's home or something, and there is no reason for it to be there (they don't know each other, etc) that would be important.

Remember, DNA isn't really used to run a "random/unknown" DNA sample against a database like in the movies. It's more used to confirm a specific sample taken by law enforcement against a specific sample from a crime scene to determine if this is, or isn't, the same person.

FWIW, DNA evidence is relatively rarely used in court. Probably because the vast majority of cases never get to trial, but most court cases don't need DNA to prosecute. There are no criminal masterminds in reality and criminals generally are stupid, especially when it comes to leaving evidence around.

DNA has also become problematic in court cases. Juries watch too much TV and see DNA solve a case in 46 minutes. Defense attorneys will poke a million holes in DNA evidence and, once the DNA is suspect, the defendant must not be guilty, right? Otherwise the cute/handsome CSI would testify and not be challenged. Instead they brought the frumpy, overweight and near sighted guy in so the prosecutor must not be sure of his case.

Jeff

apgambrell said:

So, with all the evidence my MCs have already collected that point directly at the suspect, do they still need the DNA? I mean, they matched the unknown sample from a cold case to the DNA found inside the truck that belongs to the suspect. Do they still need to get his DNA to be 100% sure it was him?

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What evidence have they gathered?

Why did they run an unknown sample against the sample found in the truck? (I mean, really, why? What in the story made them do this?)

Now, if they've matched a unknown sample to a sample found in the truck, the next logical step seems to be to match it against a suspect. Especially since, once they have collected DNA, if they DON'T try to match it, the defense would likely bring that up in the defense.

I'm kinda questioning why they even started messing with DNA in the first place, but I don't know the specifics of your story.

apgambrell said:

The unknown sample was already in the database from a cold case and came up when they ran the samples found in the truck.

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Ask Kenpochick if they actually would run a DNA sample found in the truck through a master database instead of just comparing it to the victim's DNA (or suspect's DNA for that matter).

And, if they did, what are the odds that the old cold case would bring up a hit. Would unknown/unidentified DNA from cold cases really be in some master database somewhere?

So, with all the evidence my MCs have already collected that point directly at the suspect, do they still need the DNA?

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I don't know. What other evidence have they gathered?

Trebor1415 said:

And, if they did, what are the odds that the old cold case would bring up a hit. Would unknown/unidentified DNA from cold cases really be in some master database somewhere?

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As an anecdote, we here in Anchorage, Alaska, did have a cold murder case solved a year or so ago, via DNA comparison. A young woman named Bonnie Craig was abducted, raped and murdered about 10 years ago, her body found along a trail in a nearby state park. There was virtually no evidence pointing to the killer, except DNA. But at the time, no match was found.

About a year ago, a match was found, a man living in Vermont or New Hampshire (I disremember where), arrested for another crime, and routine DNA was taken. Turned out he had been a military serviceman stationed here in Anchorage at the time of the Craig killing, and I believe he confessed; he is spending the rest of his days in prison here.

So, yes, sometimes DNA database hits really do solve cold cases.

caw

They could certainly request that the sample be analyzed (cops ask for EVERYTHING to be analyzed and I have spent a lot of time explaining what is and what is not possible to them. I will curse CSI for the rest of my life), but you just have to understand that it's not going to be a priority even with a murder and that the 6-8 month queue in Texas is going to apply. Then, if the suspect does not already have a sample on file it will just be a generic DNA sequence that doesn't match the victim.

If someone has already been suspected of or convicted of a crime they *may* have a DNA sample on file that could be matched, but again, it's rare. Not to mention that not all of the Databases talk to each other so information may be available in one state and not hit up with another, depending on what they use. That is getting better though and some states (like mine) require anyone convicted of a felony to have their DNA put into CODIS.

Samples work great for when you have a suspect in custody. You can clear them or confirm them with the testing by comparing the sample you retrieved from the crime scene with the one you collected from your suspect. It is beyond rare for it to solve a cold case. Yes, it can happen but it's like a lightning strike.

They'll solve the crime through other means and use the DNA in the prosecution.

So if you absolutely want DNA to be used in your MS, here's what you do. Have the cop be good friends with a DNA analyst at the forensic lab. Have the murderer have a criminal record. If he convicted a felony in one of these states : Alaska, Arizona, California, Hawaii, Kansas, Louisiana, Maryland, Michigan, Minnesota, New Mexico, North Dakota, South Dakota, Tennessee, Texas, Vermont and Virginia in the last few years (check each state to get the date) he will have a DNA sample in CODIS. Then the DNA analyst friend can rush the sample and a hit will be found in CODIS.

You have to have the personal connection because otherwise it's just another sample and it's not going to be rushed.

Each state takes care of their own section of CODIS. Theoretically the meet-up of all of them occurs at the FBI level (NDIS).

What would happen would be the cop would ask the analyst, pretty please can you rush this sample, it will have my name and came in on such and such date. The analyst would say ok, but only because I owe you (they could potentially be getting into trouble depending on the political climate of the lab). The analyst would pull that sample out of order and run it with their next run. The analyst could probably give them a verbal result in a few days. (This wouldn't be ready for prosecution, unofficial result)

The problem is that if the sample in CODIS does not have a name it doesn't help them at all. Then you just find out that this person is already in the system, but you still don't know who it is. So none of this will give you a name.

The only way you'll have a name is if John Smith committed a felony in Texas a year ago, as such his DNA was entered into CODIS. DNA analysts sneaks his sample on the next run and all by themselves match the DNA to John Smith's sample already in CODIS. Now you know it's John Smith. Otherwise all you know is that you have two unknowns and they match.

One of the things I hate about CSI is that they run the DNA and come up with a name. It doesn't work that way. All you're doing is matching, so if you don't already have a name, matching won't give you a name. Know what I mean?