lauradav, I'm sorry about your friend
Hope things work out.
In the hypothetical situation that was laid out, I guess it depends on specific state laws, what the guy could be charged with. I'd think/hope he could be charged with something... what he thought he saw, was his wife's lover lying asleep in their bed, and he acted "accordingly" - whether the victim was already dead should be irrelevant - he wanted to kill him. He might be given a lighter sentence since the victim (being already dead) didn't suffer, but he still should not be allowed to just walk away.