Evidence of prior knowledge:
GSA Warned of Bomb Threats To Murrah Building Day Care Center?
McVeigh Attorneys Say Government Still Witholding Evidence (Prior Govt' Knowledge & Co-Conspirators)
OKC investigating committee concludes U.S. 'had prior knowledge of the bombing'
'We knew this was going to happen' (World Net Daily)
Is This Evidence of a Practice Run for the OKC Bombing
ATF EXPERIMENTING WITH TRUCK BOMBS IN 1994!
Bomb squad seen before blast - Federal judge said many were warned of danger
OKC BOMBING FALLOUT Feds canceled pre-blast raid (Committee head: If government had acted)
Plans to raid conspirators dropped: ATF, FBI both had informants inside white-supremacist compound