Clearly, the best strategy would be for him to seek to vacate the first conviction before the second trial. He can always move for a new trial for the first offense on the basis of newly discovered evidence. In these circumstances, I can’t see the Commonwealth opposing the motion to vacate the first conviction.
Obviously, if the first conviction is no more, then it can’t be introduced at his second trial.
But assuming, for whatever reason, that the first conviction is not vacated, could it be introduced against him?
Well, in general, it’s 404(b) evidence - a prior bad act. It’s inadmissible to show a propensity to commit the current crime. In other words, the prosecutor can’t use the prior conviction to show that he likely did the current killing.
The prosecutor can admit the prior bad act if it’s evidence of a common plan, scheme, or motive, and if the probative value of the evidence outweighs its prejudicial value. This determination would rest with the judge, but I suspect it would be excluded. Of course, it depends on the specific facts of the case.
If the accused takes the stand, he may be asked if he has a prior felony conviction, but not what it is. This is admitted only as relevant to the credibility of the accused, not his likelihood of having committed the current crime.
Finally, as a strategy decision, I’m not so sure that I wouldn’t want the jury to hear about the first conviction anyway. Again it depends on the facts, but maybe the jury’s sympathy would be piqued, given the years spent in jail for a crime that never really happened, and they’d give him a pass on the instant case.
If this is a “Ha, ha, I faked my own death” case (as I understand the movie was), the above is a good strategy decision. If it’s “Pushed overboard by the accused, presumed dead, but actually struggled to survive on a deserted island for ten years before being rescued and returned to society only to be then killed”… I might not want the jury to hear it.