Bill Barr has shown himself to be a Machiavellian manipulator and conspirator of the highest order.
How much of a trail has he left? There is always some trail, especially in the United States, where political murders are, in general, frowned on and create their own suspicions.
Barr is the long time BushFamily FIXER and has CIA ties as well as being a buttbuddy of Mueller. DeepState soldier for decades and reliably anti-Trump... should be in jail! ... ymmv