The Prisoner's Dilemma, Evil Twin Edition

| Say your evil twin successfully completes a multimillion-dollar jewel heist but leaves a DNA-tainted glove at the crime scene. The police have your DNA on file, because you and your twin have both been arrested before. Lucky for you, your twin’s genetic markers are so similar to your own that no test can tell them apart. Since the DNA is the only evidence linking anyone to the crime, and you have a solid alibi (you weren’t robbing a jewelery store, your evil twin was) you both get off scot free at trial. It could be the perfect crime, and it just happened, in Germany. [%comments]


If it were a perfect crime, there would be no DNA evidence either. As it is, the guys simply got very lucky.


Leo Katz, law professor and criminal law theorist, considers a case similar to this (not DNA, but facial identification) in his book "Bad Acts & Guilty Minds."

Richard Posner criticized Katz's hypothetical as outlandish and any decision to acquit (or downgrade the charge, as the hypo went) based on the inability to distinguish between the two as unrealistic. Hmmm....


minus the DNA, wasn't this a Columbo episode, with Martin Landau as both the twins? (I think it was called "Double Shock")


I don't get it. If the DNA could only be either me or my twin, and I am the one with the alibi, wouldn't that indicate my twin had done it? What am I missing? Should I have watched more Columbo?


#3 john: Yes, I think it was also the subject of an Agatha Christie short story.

Bobby G

How is this the Prisoner's Dilemma? Interesting story I'm just thrown off by the title of the post.

Ben D

DNA proves that it was either suspect A or suspect B. Suspect A has an alibi. Suspect B is guilty. QED. Why exactly was this guy let off?

P. Kimball

This was also an Ellery Queen story. There, however, the perpetrator leaves an encoded confession, betting that nobody will be able to decode it. (The authors assume that Queen solves the problem by decoding the message, although it's not clear to me that the message would be admissible in court or that it could be proven to be a real confession and not a false accusation.)

P. Kimball

In any case, I can think of a great many other scenarios in which it is known that one of two people committed a crime but there isn't enough evidence to say which. This case only looks particularly shocking because (a) the two people involved are twins, and (b) DNA evidence normally works well to exclude people but in this case it doesn't.

Suppose you had a case in which some object must have been stolen by one of two unrelated night watchmen, and there was no DNA evidence left at all? It wouldn't get a headline. They would just keep investigating.

P. Kimball

Actually, there was a very recent similar case in Malaysia. This one was a drug case. They arrested one twin in the house which had drugs in it, and then the other one showed up later and they arrested him too. The court ruled that the first twin was pretty clearly guilty, but unfortunately they hadn't kept proper track of them and were not sure which twin the first twin was - so both went free.


Does double jeopardy apply here? I never know if it applies for the person of for the crime.
If it does apply for the crime, and they thought the 'good' twin was guilty, accused him and tried him, only to find he was innocent, then they couldn't accuse and try his evil twin.

Didn't read the Spiegel article, tho!

Jake (San Diego)

The post is misleading. Neither article states an alibi for one brother. They were probably both there, participating along with a friend.

Craig in MN

3 & 7

The only 2 people who know for sure who did it are the twins. No one else can prove which had the alibi and which didn't. They are identical to the outside world. And you can't prove to a jury that either one is more than 50% likely to have done it.

Of course, there is another of them now has jewels/cash/etc. If one of them gets caught with that, then there will be proof of which did it.

Eric M. Jones

Locally, a woman and her boyfriend turned over a car while drunk and high. The police could not determine who was driving...They were released.


I think your statement is inaccurate: if you have an alibi, the DNA proves your twin did it. Period. The case in Germany could not exclude either and, apparently, they could not prove they both were there, though that is the suspicion. This makes sense as a result; you can't convict the wrong person on a 50:50 chance he's the guy.


No, he doesn't have an alibi, he just wasn't convicted.

This doesn't prove that it's possible to commit a perfect crime. We already knew that, anyway. This just proves that DNA evidence is not a "Win every case" button. The police need to do a better job next time.

Aaron Luchko

#4 kdg:

Presumably the innocent twin doesn't want the guilty one to go to jail. Thus he simply fails to provide an alibi, remains a suspect, and thus they both remain free.


Alibi is maybe a poor choice of words in this case. It is meant here to mean that your twin was comitting the crime so you couldn't have. But even if say one of you was, say, caught on surveilance video miles away at the time, how do you know which one was the one with the alibi?

Olli Mahlamäki

To Ben D:

Subject A's alibi is that it could have been subject B. And vice versa. No way to know which one. Therefore neither is guilty beyond reasonable doubt.

the Gooch

It reminds me of Family Circus cartoons where Billy would get blamed for something Not Me did.