I admit I'm not as up to snuff on the bombing of the Murrah building as I should be, but for what it's worth, here's one theory
about others being involved with Tim McVeigh...
http://www.whatreallyhappened.com/RANCH ... OK/ok.html
PS: I was watching a segment on this event last evening on the History channel. My husband said that, if Georgy Bush had been president in 1995, the invasion of Iraq would've taken place as retaliation for the Oklahoma City bombing regardless of whether or not there was any connection to Iraq involvement.
AND as a companion piece, go here to read up on Officer Yeakey, the role he played in OKC that day, and his subsequent "suicide" in 1996: