Can DNA effectively be extracted from sweat?

October 6, 2006 9:11 PM

Can DNA effectively be extracted from sweat?

So, I was mugged last night. "hey mate..." "yeh?" (ubu turns around) *king hit to side of head*; mugger one grabs me by the lapel with raised fist, mugger 2 goes through my pockets. mobile phone & inconsequential amt of cash taken. wallet returned, kindly. (saved some bureaucratic hassle, al-hamdu li'llah!)

anyway, the coppers took the wallet & coat off me when i reported this, to be sent for dna sampling. the only trace that could be on either would (presumably) be any sweat that they were excreting. i am assuming that this kinda thing would be as adrenalised for them as it was for me. so...what chances of dna'ing them?

posted by UbuRoivas to science & nature (13 comments total)

Skin flakes are amazing things.
posted by flabdablet at 9:19 PM on October 6, 2006

Wow, they go to such an extent there? Around here you'd get your name taken and then uh, that would probably be it.
posted by digitalis at 9:22 PM on October 6, 2006

We had a crazy druggie homeless guy steal a computer from our shop about two years ago. There ended up being quite a tussle between him and the boss, and the boss wound up pulling the guy's shirt off. Again, the Sydney coppers took the shirt for apparent "testing." Never heard anything back from it though. Maybe they're building a database or something.
posted by web-goddess at 9:31 PM on October 6, 2006

digitalis: yeh, i was surprised, as well. this is in a pretty busy, inner-city part of sydney. it actually took about an hour and a half to take down my statement & do the dna thing (they took mine as well, along with accompanying legal docs that it would not be used to investigate me; i have the right to ask for my records to be destroyed etc etc.) i was served by no less than one sergeant & two detectives (!).

funny bit: "he was holding me by the lapel"
(fem)copper: "what's that?"
"it's like an extension of your suit's collar, it runs down across your chest, like this"
"oh, a collar, then" *types statement*: "he was holding me by the collar..."
posted by UbuRoivas at 9:31 PM on October 6, 2006

Sure can, you can get enough DNA from fingerprints for a forensic sample if the crime is serious enough to justify the work.

I'm not sure of the rate of matches in aus, but here in nz any DNA sample taken from a crime scene has a roughly 50% chance of leading to a match of someone in the database, and an arrest.

I'm guessing they are taking it so seriously due to the assault before even asking for money, that's quite an aggravation from someone threatening violence.
posted by scodger at 9:34 PM on October 6, 2006

flabdablet: yeh, and in victoria, they just shoot you.

web-goddess: yeh, database would be the deal. (this is starting to feel like livejournal ;) ) - idea being that if they have these guys on the database they can look them up, if not, i guess it's a matter of waiting & luck for them. ice (meth, for youse americans) junkies would be my guess. nowhere near pathetic & useless enough to be the traditional heroin junkie.
posted by UbuRoivas at 9:36 PM on October 6, 2006

what chances of dna'ing them?

Due to possible contamination from others (friends, family members etc.) handling your coat and wallet: practically and legally near-zero.
posted by Blazecock Pileon at 9:39 PM on October 6, 2006

blazecock: well, nobody touches my wallet other than me & muggers. the coat is one that i almost never wear. once, this winter, from memory. so, fingers crossed...?
posted by UbuRoivas at 10:01 PM on October 6, 2006

Well, your DNA is almost certainly going to end up in that database along with the muggers. Don't plan on murdering anyone.
posted by delmoi at 10:05 PM on October 6, 2006

Don't plan on murdering anyone.

SHIT!!! JonBenet! I had forgotten about her!

*flees to Majorca*
posted by UbuRoivas at 10:07 PM on October 6, 2006

(fem)copper: "what's that?"
"it's like an extension of your suit's collar, it runs down across your chest, like this"

Oh my, that is funny!

And flabdablet...*groan* But I so deserved it.
posted by digitalis at 11:40 PM on October 6, 2006

Too many skin flakes to get any kind of accuracy w/ traditional PCR amplified DNA samples. think about how many more of yours and your friends' skin flakes would be on there, the people who see and touch your clothes all the time. (sweat has almost no DNA)

Maybe if he had a cut on his finger, or if he left a couple hairs to find? I'd cross my fingers on that possibilty more than anything.
posted by wuzandfuzz at 2:47 PM on October 7, 2006

This article claims to be able to PCR-amplify and genotype DNA from sweat latent fingerprints. The article's in Chinese, so I can't really assess how well it was done. Plus, as others have pointed out, you'd have to get samples from everyone you know so they could rule them out and NOT add them to the database.
posted by ObeyScient at 11:08 PM on October 11, 2006