An unlikely scenario but one I've always wondered about:

Let's say that a murder was committed. There is a pair of identical twins. Both twins had means, motive, and opportunity for the murder.

It has been proven beyond reasonable doubt that one of them committed the crime. A witness actually saw one of the twins stab someone, to death but he can't tell which one. The knife has been found, and has the twins' DNA on it. Of course, their DNA is identical, so it is evidence that one of them did it, but tells us nothing about which one. Neither twin has been able to establish an alibi.

Am I correct in assuming that a conviction is impossible, because either twin could argue that the other did it? What if one twin established an alibi, would that be sufficient to convict the other?

  • Yes identical twin's DNA is identical but there is other forensic material that you can use to distinguish twins with but that may not exist in all situations. Nov 22, 2016 at 23:55

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A conviction isn't ever impossible, but it could well be highly unjust. Indeed, there is a current case where a man alleged that he was the murder, though his identical twin brother was convicted. This article indicates that identical twins are not necessarily genetically indistinguishable. Assuming there is a lack of positive evidence such as fingerprints or an alibi which clearly identifies one versus the other, then one would predict no conviction because there would be a highly reasonable doubt. See the case of Orlando Nemnhard, where one of two twins did it but the DA concluded that they couldn't prove which one, so the charges were dropped.

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    I was a victim of road rage a number of years ago. The perpetrator tried to get at me but I locked all doors from inside. He took it out on the car instead, rendering kicks to the bodywork, denting it in several places. He sped off. Police ascertained it was a hire car, rented out to twin brothers. Police informed me that they couldn't charge (criminal damage) anyone as only one twin was in the car at the time, each twin fingering the other when interviewed at the station. I thought this a classic case of 'conspiracy to pervert the course of justice". Police declined to run with that Nov 20, 2016 at 16:06
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    @PeterPoint I don't they could prove that either, as they know one of the twins was not involved in the road rage, he might just be telling the truth, while the other one is lying. But you're faced with the same problem as not knowing which one is which. Nov 21, 2016 at 19:51

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