How exactly does an armed robbery turn into a murder? Someone has to pull the trigger. Someone has to make that decision. TB grabs the gun, the shooter pulls the trigger. Did TB just preempt the shooter's intended action?
I think not having the background on the other cases makes this case stronger. I doubt they will bring the Harley into this, even. It's the story arc of abduction, murder, incineration, a breathtakingly fast flow of action on the part of DM and MS that make this seem like a planned act.
Yes, I get the feeling they don't want to muddy the case with other violations. Like they said there was only 1% material on the computer that was relevant to this case. I doubt the other 99% didn't incriminate him in other things he may be charge for at another time.