The one that left scars on me was the case of Timothy Evans. He was hanged for killing his wife and daughter. At his trial, his defence lawyers alleged that the murders had been carried out by his neighbour, John Reginald Halliday Christie, who was a necrophiliac, sexually inadequate with living women. At the the time, nobody believed them (who would?), but it was later shown that the allegation was very probably correct, despite having been thought too fantastic to be true. The doubt was judged to be not reasonable. Christie was later hanged for a series of murders, but that was too late for Timothy Evans, who was later pardoned, posthumously. You might say that this could never happen in the USA, but are you sure of that?

If you also read Sir Sydney Smith's autobiography "Mostly Murder", you will see that he had significant doubts about some other cases, although proof of innocence was never forthcoming in any of them. It's often a question of who the jury believes. Proof is very difficult to come by in cases like these, and I hope you will understand that I still have doubts, especially in cases where the accused maintains his/her innocence right to the end. Even if it is intentionally made difficult to prove guilt, it can be still more difficult to prove innocence once someone has been found guilty. As with Timothy Evans, truth sometimes is stranger than plausibility.