A successful and smart conspirator would be certain to have no records and to be verifiably elsewhere for the assasination,bombing,fire,train wreck or whatever.
Have a patsy do the deed then have him silenced by another who is ignorant of the original conspiracy.
Does not the spy world excel in manipulation?
Perhaps you can say what HW and W were doing that day.
If you are going to conduct an assassination conspiracy—and get away with it you need at a minimum:
—Control at the top of the relevant law enforcement authorities
—Control over mass media coverage
In the case of the US/Kennedy assassination that would only be possible with LBJ, CIA and FBI involvement from day one.
The CIA had Operation Mockingbird for mass media control—and of course the ability to put together assassination teams—lots of practice abroad.
However they could not manage a coverup (which still continues to this day) without LBJ’s cooperation and FBI involvement.
Since LBJ is long dead we need only look to the CIA and FBI to find agencies still linked to the assassination.