I am 100% convinced Mark Smich pulled the trigger. For him, this was the "gangsta moment" he so craved. This was his notch on the gangsta scorecard.
Think about it logically. The only reason MS has not spilled the beans and come clean is because he's the one that pulled the trigger. Otherwise, if DM pulled the trigger, I guarantee MS would volunteer to be a witness. He has no more reasons to remain loyal to DM. This is about saving one's own rear end now. Survival of the fittest. It's like a night club fire when people trample on people to get out in order to save themselves. The only reason MS is remaining quiet is because he's the trigger man. He's secretly hoping to have DM take the bulk of the blame, and somehow get a lesser sentence for himself.
DM has already said "it's there for everyone to see". I think there is some truth in that.
However, DM and MS are equally guilty of 1st degree murder, without any doubt in my mind. Neither one should be considered less culpable. Both are equally guilty.
We do not need MS or DM to tell us the "truth". The evidence and common logic tells us everything we need to know.
Put them away forever.