How long does a DNA match take?

Factual Questions
1

A criminal leaves a trace of their DNA at a crime scene. A suspect has been found, and a DNA sample taken. How long does it take to test, and declare a match or no match?

I’m talking about the actual lab procedure. I am aware that the investigators might have to wait several weeks to get a result. But that’s because there’s a long backlog of tests waiting to be done. Once the actual test starts, how long before the result comes?

Yes, I’ve tried googling. The only information I’ve found is about backlogs and waiting lists.

2

Found this: “Depending on the laboratory, results can take as little as 2 working days to come back from the receipt of samples.”

3

Less than a day for the actual lab work.

4

As an undergrad I took molecular genetics and ran gels in the lab portion of the lab portion of the class. I’m sure the process is more complicated for a human than for the bacteria we were dealing with, but probably runs on the same principles. If so, my guess is a few hours.

5

Would that be a few hours of walking around with a timer in your lab coat pocket while doing other stuff or a few hours of serious hands-on work?

6

Back in the day most of the time for any given experiment was waiting for the gel to run. Of course we weren’t just waiting around with a timer. We would be working on setting up the equipment and supplies needed for the next experiment, cleaning up the equipment we had already used, and doing that stuff for the graduate students and professor as well. Labs don’t maintain themselves :sweat_smile:.

ETA: By most of the time, I mean something like about a little over 1/2 to about 2/3, not 99+ percent.

7

Yes, I figure you can certainly do it in a few hours (including

if you have the right automated equipment, e.g.

which is not even bleeding-edge technology. Seems like 80 minutes for the actual PCR, a couple of hours for capillary electrophoresis

8

We’ve had DNA analysis done on several dogs (Wisdom is the company, I’d recommend them highly).

I ended up chatting online with a lab worker there about the process. Once they receive the sample, they keep in touch with you and have results in about one week. I found out that the week is partly due to the volume of tests they are doing and partly an intentional delay to give their product better apparent value.

9

And don’t forget about the PCR to amplify the initial sample.

But “waiting for the gel to run” implies you’re just doing an electrophoresis fingerprint (which is, admittedly, probably good enough for matching a suspect to a sample). What if you want a full sequencing for some reason?

10

And here is an outfit promising results in 90 minutes.

11

We didn’t get around to full sequencing, so I’m not directly familiar with that process.

12

Doesn’t your link say the final step could take 24 hours?

Rather those are specs, the machine CAN hold for 24 hours. Ok, why would it if it never needs too?

13

If I recall correctly, when the United States launched that 2019 commando raid to kill Abu Bakr al-Baghdadi (the leader of ISIS) in Syria, Baghdadi blew himself up with a suicide vest, but the commando team did an immediate DNA test of his flesh on the spot and confirmed, within minutes, that it was him.

14

If looks like comparing two samples together is quick. Comparing one sample to the entire database to find a match is a longer process.

15

For that matter, there are ways to compare two samples without even learning anything (other than the degree of match) about either sample. Basically, you unzip two pieces of DNA, and see how well they zip with each other.

16

Not really

17

Possibly if you wish to store the PCR products, or some of it, for later? The manual also says you can program an unlimited hold time if you want, and to store the amplified DNA in the refrigerator (or freezer if you are going to store it longer than 2 weeks). I don’t know firsthand how those machines get used in the FBI lab so no idea if there is never a need to hold for 24 or more hours.