Former Sen. John Danforth said the FBI was so uncooperative in his Waco investigation that he threatened FBI Director Louis Freeh with a search warrant to gain access to relevant documents, Danforth told The Washington Post.

As special counsel, the Missouri Republican conducted a 14-month investigation into the deaths of about 80 Branch Davidians in Waco, Texas, in 1993.

His inquiry was aimed at determining whether the FBI started a fire that led to the deaths of those inside the religious sect's compound and whether FBI agents opened fire. Danforth's investigation concluded that the FBI did neither.

The process of gaining information from the FBI was harrowing for him, Danforth said. He told the Post that the agency had a "spirit of resistance" to outside authority.

While Danforth said it is possible the FBI did not turn over all of its documents on the subject, he doubts that documents were withheld that had any bearing on his investigation.

"It was like pulling teeth to get all this paper from the FBI," Danforth said.

"Can I say to you that there isn't some box of paper somewhere that we never found? I can't say that to you," he said. "Do I think there is any chance that it would be paper that would have any effect on our findings? I think there is no chance that it would have any effect on our findings because the evidence was so overwhelming."

Danforth was appointed special counsel by then-Attorney General Janet Reno after officials disclosed that incendiary tear gas canisters were launched inside the Davididan compound -- something that had been denied for years by the FBI and the Justice Department.

His comments come as the FBI tries to explain why it did not turn over 4,000 pages of documents to defense attorneys for convicted Oklahoma City bomber Timothy McVeigh. McVeigh has asked for a stay of his execution.