why? Say someone is murdered, and it doesn't take much forensics to determine that they were attacked, restrained while alive, then shot in the back of the head execution style.

Or maybe it's even more blatent. police find a note from the day before that says "im going to kill you" then they end up dead.

Would you construe that the commission of those murders was premeditated? almost certainly yes, ergo whoever it gets pinned on, innocent or not will get premeditation applied, it doesn't take much extra here.