Bill Clinton staged the OKC bombing.
There had been plots on the building by persons McVeigh had reportedly associated with going back over a decade.
There were also possible foreign ties to the attack. Certainly there were more than 2 persons involved (and some were granted plea deals in exchange for testimony).
McVeigh and Nichols were guilty but there was a lack of will to prosecute all involved, especially following up on leads suggesting foreign involvement.