NEW YORK, May 29, 2001 (CBS) Four FBI agents involved in the Oklahoma City bombing investigation have told 60 Minutes II that they were not surprised that evidence was not turned over before trial, causing a delay in the execution of Timothy McVeigh.

One agent says evidence that he personally obtained - evidence that might have helped McVeigh's case - may have been ignored or not documented by the FBI. Rob Nigh, McVeigh's attorney, says the new information will change the course of his client's case in the near future.

Rick Ojeda received a commendation for his work on the Oklahoma City bombing case, but was later fired in what he calls an act of retaliation for bringing discrimination complaints against his bosses. In March 2000, Ojeda stated in a letter to Sen. Charles Grassley (R-Iowa) that he was aware of cases, including the Oklahoma City bombing, where exculpatory evidence was ignored and not documented. He also said that he personally gathered some of that evidence.

"I started thinking and I started going back and checking to see if some of the information that I had provided had ever been mentioned at trial, and I talked to a couple of agents that worked the case and asked them about leads that I had done - whether they were ever brought up," says Ojeda. "I even asked them to check to see if some of the [documents] that I had mentioned had ever been turned over and they couldn't find them and so I started to wonder if the stuff had been withheld or just lost, which was common," says Ojeda.

Veteran FBI agent Jim Volz was also on duty the day McVeigh destroyed the Alfred P. Murrah federal building. He reviewed the FBI's internal documents on the bombing, including interview notes, witness statements, sightings and tips. "It's extremely surprising to me that these documents all of a sudden show up," says Volz. "There's no reason for it unless there is negligence."

Dan Vogel was the FBI's public voice in Oklahoma City during the bombing investigation. Vogel says he's concerned that the FBI waited until a week before McVeigh's execution to reveal the missing documents. "If you're not turning them over, you're obstructing justice," says Vogel.

"There was as cultural problem in the FBI that needed to be addressed, otherwise it is going to destroy itself," says Vogel. "You see the FBI is made up of a lot of very fine, dedicated people. And these people deserve better, the American public deserve better, and these recent revelations where we have a man scheduled for execution and all of a sudden we find documents that haven't been turned over to the defense attorneys or to the prosecution a week before the execution, that really made up my mind, after that there was no question in my mind that I needed to come here today and do whatever I could to - to try to get this changed."

60 Minutes II shared the information provided by the FBI agents with McVeigh's attorney Rob Nigh. "That information should, at minimum, change the course of this case in the near future," says Nigh. "If those statements [provided by the FBI agents] are accurate, the verdict has no integrity and we cannot possibly proceed with an execution until we know... These agents have indicated that there is at least a possibility of misconduct rising to the level of criminal misconduct in Tim McVeigh's case. The importance of this information cannot be overstated... I was absolutely overwhelmed."

In all, 4,034 pages of materials about the April 1995 bombing of the Alfred P. Murrah Federal Building have been found that should have been turned over to McVeigh's attorneys years ago. The FBI says computer and record-keeping blunders caused the problem and that some documents were not material to the case.

McVeigh's execution was delayed this month until June 11 after Justice Department officials acknowledged the existence of the documents.

Attorney General John Ashcroft Thursday insisted none of the new evidence bears on McVeigh's conviction or sentence and said no further delay would be necessary.

Nathan Chambers, a member of McVeigh's legal team, said Saturday he could not comment on any of the FBI documents. He said attorneys had not yet decided whether to seek a new trial or a stay of execution.

A court order prevents the Justice Department from releasing the evidence to the public or describing it in detail. Among the evidence found, according to Ashcroft, were:

Newspaper, magazine clippings and a swimsuit calendar from a person in psychiatric care. "Most of these clippings did not pertain to the bombing," the attorney general said. Correspondence from a person offering unspecified information in exchange for getting a person released from prison, a large cash award and a trip to Europe. Letters containing information about "non-physical beings" and "offers by psychics to contact victims for information on the bombing." Documents recording services of subpoenas and other routine legal matters.

Ashcroft Thursday said the evidence also contained fingerprint cards and criminal history reports of "persons who turned out to have no connection to the case."

The Oklahoma City Bombing and the Reichstag Fire