You keep talking about Comey. Why?
Mueller was Director of the FBI at the time and had a case on the whole family for years.
Mueller is famous for keeping four men he knew were innocent in jail for life, in order to protect Whitey Bulger. Putting Tsarnev to death to protect the real bomber is a perfect fit for his MO.
So Comey vs. Mueller doesn’t really make a material difference does it.
Anyway, Comey is up to his eyeballs in this as well.