This is a murder case.
Despite his denial, there is a witness who p[laces him at the scene of the crime. If he is part of a robbery and some is stabbed to death, he is just as guilty of murder as the one who held the knife.And, I don't think he has a good case for a separate trial.
What is going to happen is that after enough time witnesses die, forget, move away or otherwise disappear. Essentially, he is trying to get away with murder, and just may do it.
Are the prosecutors delaying at gun point?
If the damn prosecutors are so incompetent that they can't build a case against this guy in 7 years then it's not the defendant's problem....