Gosh, that is a tough one. I watched them over the weekend, and while I'm sure there's something distinctively different, I am unable to pick it out. It will be interesting to see the reveal!
The only one I'm pretty sure about is DEAD WEIGHT. It has a partial witness to the murder.
(Of course, DAGGERS OF THE MIND has a witness to the accidental killing, but both characters are actually part of the killing, so that puts it in a different category.)