No it wouldn't. She would have said that it was him, they would have believed her (as they did when she claimed that), arrested him and sent him to prison for the rest of his life.
If you had lived a moral straight arrow life you might think that the truth would come out if you were in a situation like that, but that isn't how things work. You would have to prove your innocence, guilt would be assumed, and doing that is not as easy as you seem to think. All the prosecution would need is to persuade a jury that there was no reasonable doubt (not absolute proof), which is not hard to do because most juries go into court rooms assuming that if you are prosecuted you are likely guilty. Unless the prosecutor is clearly stretching you would allmost certainly be convicted.
Someone like Rafferty who lives a dubious life would certainly be streetwise about that, and if they find themselves in that sort of situation I can guarentee you that 99% of the time they will keep quite about it because they are not stupid.
Given what we know about McClintic his story is plausible. He is not going to be able to prove it though, and the prosecutor is probably not going to be able to prove that she is telling the truth. That leaves it with the jury and as I said, unless there is a clear cut case one way or the other a jury will allmost allways convict.
Even if he was the one to come forward to the police at the start, he would still be standing where he is now, facing exactly the same situation.
A word of advice, if you ever find yourself in a similar situation, you are best advised to keep quite about it, unless you really want to spend most of the rest of your life in prison.