# DNA trickery - has this plot device ever been used in a crime story? **URL:** \ **Category:** Cafe Society\ **Created:** [May 22, 2007, 11:34pm UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156 "2007-05-22T23:34:19Z")\ **Posts on this page:** 15\ **Page:** 2
**Author:** ![Doctor\_Who](https://avatars.discourse-cdn.com/v4/letter/d/ed8c4c/32.png) [@Doctor\_Who](https://boards.straightdope.com/u/Doctor_Who)\ **Post date:** [May 23, 2007, 3:36pm UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/21 "2007-05-23T15:36:45Z")
[This news article](http://abcnews.go.com/TheLaw/LegalCenter/story?id=3195632&page=1) is not exactly on point, but it’s just so damn relevant (plus I saw it on CNN this morning and I thought you guys might be interested). For the link impaired, it’s about twin brothers embroiled in a paternity suit. ---
**Author:** ![Quercus](https://avatars.discourse-cdn.com/v4/letter/q/7ab992/32.png) [@Quercus](https://boards.straightdope.com/u/Quercus)\ **Post date:** [May 23, 2007, 3:58pm UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/22 "2007-05-23T15:58:29Z")
[QUOTE=bouv] [DNA evidence proved one twin committed the crime but] both used the alibi of seeing a movie with the other. Since [the cops] knew they couldn’t get one to rat out the other, they had to let both go free. [/QUOTE] Hmm. I’d say if the twins actually testified under oath to their alibi, then they screwed up, because now they can both be convicted of perjury (and/or aiding a criminal, conspiracy, etc.). After all, they can’t both have been at the movies, so twin A either lied about being at the movie, or lied about twin B being there. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [May 23, 2007, 4:11pm UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/23 "2007-05-23T16:11:32Z")
[QUOTE=Yllaria] Which book was it? It was a Kay Scarpetta mystery. The killer turned out to have gotten a bone marrow transplant from a sibling, so that the DNA in the blood he left behind wasn’t his DNA. Not quite a twin problem, but I thought it was a nice DNA twist. [/QUOTE] I remember the bone marrow donation angle from somewhere, but I know I haven’t read any Kay Scarpetta mysteries. It might have been an episode of CSI or another police procedural. ---
**Author:** ![jsc1953](https://avatars.discourse-cdn.com/v4/letter/j/5daacb/32.png) [@jsc1953](https://boards.straightdope.com/u/jsc1953)\ **Post date:** [May 23, 2007, 4:26pm UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/24 "2007-05-23T16:26:17Z")
The uncertainty caused by identical twins was indeed a **Without a Trace** episode, from 2 seasons back IIRC. \*\*CSI \*\*(also, 2 seasons back) had an episode where DNA didn’t pinpoint the actual killer (at first) because he had chimera syndrome, and carried 2 different sets of DNA. ---
**Author:** ![Terrifel](https://avatars.discourse-cdn.com/v4/letter/t/c68b51/32.png) [@Terrifel](https://boards.straightdope.com/u/Terrifel)\ **Post date:** [May 23, 2007, 4:29pm UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/25 "2007-05-23T16:29:25Z")
[QUOTE=bouv] Are you thinking of the SVU episode? Cause it doesn’t go quite like you have in the spoiler. It wasn’t so much that the twin sister did it as it was they couldn’t tell which one did it, because they kept their back to the security cameras (the sister, from hormone therapy, still appeared feminine,) and obviously all the DNA matched both, and both used the alibi of seeing a movie with the other. Since they knew they couldn’t get one to rat out the other, they had to let both go free. [/QUOTE] Well, possibly I’m deranged. My memory is like a lumber-room, in that it has lots of bugs and sawdust in it. At least I didn’t confuse the plot with that one episode of **What’s Happening?** when Rog’s evil twin\* showed up. Now I wonder if anyone’s done the reverse of the story-- where somebody gets away with murder because their DNA has somehow changed in the meantime. Or was that the plot of **The Shaggy D.A.**? \*I think it was his evil cousin, actually. To my recollection, no DNA was harmed. ---
**Author:** ![Arnold\_Winkelried](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@Arnold\_Winkelried](https://boards.straightdope.com/u/Arnold_Winkelried)\ **Post date:** [May 23, 2007, 6:21pm UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/26 "2007-05-23T18:21:55Z")
[QUOTE=Doctor Who] [This news article](http://abcnews.go.com/TheLaw/LegalCenter/story?id=3195632&page=1) is not exactly on point, but it’s just so damn relevant [/QUOTE] If only I had thought to mention that in the OP! ---
**Author:** ![Arnold\_Winkelried](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@Arnold\_Winkelried](https://boards.straightdope.com/u/Arnold_Winkelried)\ **Post date:** [May 23, 2007, 6:23pm UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/27 "2007-05-23T18:23:12Z")
[QUOTE=Steve MB] it’s a fairly dull and predictable plot turn, tedious, unoriginal, and lacking in any true insight. [/QUOTE] When I get a million dollars for my screenplay, both you and Chronos are officially uninvited from the celebration party. ---
**Author:** ![Arnold\_Winkelried](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@Arnold\_Winkelried](https://boards.straightdope.com/u/Arnold_Winkelried)\ **Post date:** [May 23, 2007, 6:53pm UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/28 "2007-05-23T18:53:32Z")
I think I might have read that Kay Scarpetta mystery - the title might be “All That Remains”. ---
**Author:** ![Doctor\_Who](https://avatars.discourse-cdn.com/v4/letter/d/ed8c4c/32.png) [@Doctor\_Who](https://boards.straightdope.com/u/Doctor_Who)\ **Post date:** [May 23, 2007, 7:10pm UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/29 "2007-05-23T19:10:09Z")
[QUOTE=Arnold Winkelried] If only I had thought to mention that in the OP! [/QUOTE] :smack: I read the OP carefully, I promise. Only I read it yesterday. Here’s another headsmack for good measure: :smack: ---
**Author:** ![Arnold\_Winkelried](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@Arnold\_Winkelried](https://boards.straightdope.com/u/Arnold_Winkelried)\ **Post date:** [May 23, 2007, 7:16pm UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/30 "2007-05-23T19:16:47Z")
Don’t smack yourself too hard, Campion did the same thing. ---
**Author:** ![Weirddave](https://avatars.discourse-cdn.com/v4/letter/w/919ad9/32.png) [@Weirddave](https://boards.straightdope.com/u/Weirddave)\ **Post date:** [May 24, 2007, 12:48am UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/31 "2007-05-24T00:48:43Z")
I don’t remember if there was a DNA angle, but multiple identical people factored heavily into the plot of Ken Follett’s book _The Third Twin_. ---
**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\ **Post date:** [May 24, 2007, 1:27am UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/32 "2007-05-24T01:27:29Z")
It’s been a while since I’ve read Presumed Innocent, but I don’t remember DNA evidence coming up(mostly because the defendant was found not guilty without the crime being solved, and there’s no way that he would have been found innocent had his DNA been found at the scene). Although now I have a hazy memory of the medical evidence being discredited, so many DNA evidence did come into play. ---
**Author:** ![Saltire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saltire/32/553_2.png) [@Saltire](https://boards.straightdope.com/u/Saltire)\ **Post date:** [May 24, 2007, 2:03am UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/33 "2007-05-24T02:03:01Z")
[QUOTE=Rysto] It’s been a while since I’ve read Presumed Innocent, but I don’t remember DNA evidence coming up(mostly because the defendant was found not guilty without the crime being solved, and there’s no way that he would have been found innocent had his DNA been found at the scene). Although now I have a hazy memory of the medical evidence being discredited, so many DNA evidence did come into play. [/QUOTE] [spoiler]It wasn’t DNA, as that test wasn’t really an option then. The semen found in the dead woman matched the guy’s blood type, and they were able to prove he was having an affair with her. But when the lab found spermacide in the semen, but no source for it at the scene, the defense argued that the lab sample must have been mixed up or corrupted somehow. But it turned out that the real killer had placed the semen there after obtaining the sample from the protagonist herself in the usual way. Except she used a diaphram, thus the spermacide.[/spoiler] ---
**Author:** ![Eureka](https://avatars.discourse-cdn.com/v4/letter/e/74df32/32.png) [@Eureka](https://boards.straightdope.com/u/Eureka)\ **Post date:** [May 24, 2007, 2:54am UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/34 "2007-05-24T02:54:45Z")
Thank you, **Saltire** , for clarifying the details. Now I won’t have to re-read the book in question. (As I recall, it was a book I finished because I “needed” to figure out how things were resolved, rather than because I was enjoying the book so much. ) ---
**Author:** ![Steve\_MB](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/steve_mb/32/5339_2.png) [@Steve\_MB](https://boards.straightdope.com/u/Steve_MB)\ **Post date:** [May 24, 2007, 1:31pm UTC](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156/35 "2007-05-24T13:31:20Z")
[QUOTE=Arnold Winkelried] When I get a million dollars for my screenplay, both you and Chronos are officially uninvited from the celebration party. [/QUOTE] Just the reaction I was looking for to get the evil twin to give himself away. [Take 'im away, boys!](http://www.giantitp.com/comics/oots0363.html) [Previous page](https://boards.straightdope.com/t/dna-trickery-has-this-plot-device-ever-been-used-in-a-crime-story/405156.md?page=1)