Several of the documents were not provided to the bomber's defense before he was convicted. And the FBI agent in charge of the investigation says he never received one teletype from his own headquarters that raised the possibility McVeigh was aided by other accomplices.

"They short-circuited the search for the truth," McVeigh's original attorney, Stephen Jones, said in an interview. "I don't doubt Tim's role in the conspiracy. But I think he clearly aggrandized his role, enlarged it, to cover for others who were involved."

McVeigh was executed in June 2001.

Evidence gathered by The Associated Press includes hotel receipts, a speeding ticket, prisoner interviews, informant reports and phone records that suggest McVeigh had contact with a white supremacist compound in Oklahoma known as Elohim City and that members there were familiar with his plan.

"It is suspected that members of Elohim City are involved either directly or indirectly through conspiracy," federal agents wrote in one memo just days after McVeigh detonated a truck bomb April 19, 1995, outside the Alfred P. Murrah federal building (news - web sites) in Oklahoma City and killed more than 160 people.

The documents also include a teletype from FBI headquarters in August 1996 that reported McVeigh called Elohim City two weeks before his bombing, a call to a home where members of a violent Aryan Nation bank robbery gang were present.

McVeigh made the call April 5, 1995, moments after calling the Ryder truck company where he rented the truck that carried his deadly bomb. The government had known from an informant weeks before McVeigh's call that members of Elohim City were threatening an attack, the documents show.

The FBI teletype revealed that the gang members who were present when McVeigh called were familiar with explosives and had made a videotape three months before McVeigh struck vowing a war against the federal government and promising a "courthouse massacre."

The Murrah Building was across the street from the federal courthouse in Oklahoma City.

The teletype also noted that two of the robbers left Elohim City on April 16 for a location in Kansas a few hours from where McVeigh was doing the final assembly of his bomb.

"I did not see that teletype," retired agent Dan Defenbaugh, who supervised the Oklahoma City investigation, told AP.

Defenbaugh said that while he didn't consider the teletype a "smoking gun" that would have changed the outcome of the probe, his investigative team "shouldn't have been cut out. We should have been kept in on all the items of the robbery investigation until it was resolved as connected or not connected to Oklahoma City."

Defenbaugh said he also was surprised to learn, from AP interviews and documents, that prosecutors in 1996 made and then withdrew a plea bargain offer to one of the imprisoned bank robbers, Peter Kevin Langan, who claimed he had information about the Oklahoma City bombing.

"The Justice Department (news - web sites) came to us through the assistant U.S. attorney and said, 'We believe your client knows about Oklahoma City and we want to talk to him. We want to work out a deal,'" Langan's lawyer, Kevin Durkin, told AP.

Langan made several demands the government wasn't willing to meet, and prosecutors dropped the request, Durkin said.

Durkin said his client has information about the Oklahoma City bombing, and had planned to tell prosecutors that he could disprove the April 19 alibis for two of the bank robbers mentioned in the FBI teletype.

Langan recently asked a court to stop the government from destroying evidence he claims may be relevant to the Oklahoma City case. A document obtained by AP on Wednesday shows the FBI was ordered by prosecutors to destroy evidence from the robbery, including the videotape, even though appeals were pending.

FBI officials acknowledged some of the documents were not provided to McVeigh's defense team before his trial. For instance, they said FBI teletypes were not covered by the agreement governing documents to be given to McVeigh's defense.

They also acknowledged that agents suspected at one point that the bomber was linked to Elohim City and the Aryan Nation bank robbers.

But they said that after more than 1 million investigative hours that generated more than 1 billion documents and checked 43,000 tips, FBI agents found no concrete evidence of McVeigh conspirators beyond Terry Nichols, who is in federal prison.

"Every lead, regardless of its credibility, was thoroughly investigated to its conclusions," spokesman Mike Kortan said Wednesday. "While conspiracy stories continue to circulate, no evidence that other individuals were involved in the bombing was corroborated by the investigation."

Defenbaugh said one of the challenges for the investigation was that there were a large number of white supremacists who shared McVeigh's hatred for the government and talked of similar plans.

"Even though we had our conspiracy theories, we still had to deal with facts and the fact is we couldn't find anyone else who was involved," he said.

The documents show the FBI suspected McVeigh participated in a December 1994 Ohio bank robbery with the Aryan Nation robbers, but lab analyses that attempted to match him to a videotape from the bank's security camera were inconclusive.

FBI officials had several reasons to suspect a connection:

_McVeigh's sister told them her brother gave her money from a bank robbery and asked her to launder it in December 1994. Also, they had evidence McVeigh was in Ohio at the time, FBI officials said.

_The leader of the robbery gang, Mark Thomas, initially told agents after his arrest that he suspected some of his members were involved in McVeigh's plot. He later recanted.

_A girlfriend of one of the bank robbers told the FBI her boyfriend had told her beforehand of a plan to bomb a federal building, and that he left days before the bombing for a trip to Elohim City. "We are going to get them. We are going to hit one of their buildings during the middle of the day. It is going to be a federal building," n FBI report quoted the bank robber as telling the girlfriend.

FBI agents stopped pursuing possible connections between McVeigh and the robbers when the suspects all denied assisting the Oklahoma bomber. Most weren't given lie detector tests, officials said.

The robbers, however, weren't the only evidence that led the FBI to suspect a link between McVeigh and Elohim City.

Agents collected a receipt showing McVeigh stayed at a hotel near the compound on Sept. 13, 1994, the day that, a federal grand jury concluded, he hatched his plot to blow up the Murrah Building. The hotel was about 20 miles away in Vian, Okla., one of the closest cities with a hotel near the compound. The FBI also obtained a speeding ticket McVeigh received just 12 miles from the compound.

They also interviewed a witness who had aided government prosecutors in other white supremacist cases.

John Shults told agents in 1997 he was "sure beyond a shadow of a doubt" he saw McVeigh at Elohim City in 1994 at a meeting about a mysterious delivery and the use of a Ryder truck. Shults "felt strongly the delivery may have been a reference to the bombing," according to one federal agent's interview report.

AP reported Tuesday that the government had informant information well before the bombing indicating members of Elohim City were discussing bombing a federal building in Oklahoma and that the FBI specifically had worries such an attack could occur April 19 after interviewing a reformed white supremacist familiar with an earlier plot to blow up the Murrah building.

Within a few days of the bombing, FBI officials received intelligence suggesting members of Elohim City had information relevant to the investigation.

Carol Howe, the Bureau of Alcohol, Tobacco and Firearms informant who had provided information that Elohim City members were discussing an attack, was sent back to the compound in late April 1995.

Howe talked with one member of the compound who "discussed alibis for April 19, 1995, and the components of" McVeigh's bomb, investigative memos show. The same member had claimed, before McVeigh's bombing, that he had detonated a 500-pound fertilizer bomb, similar to the one McVeigh later used.

That compound member also discussed the name of a munitions dealer that McVeigh's phone records showed the bomber called more than two dozen times in the weeks before the attack. McVeigh had the dealer's phone number in his wallet when he was captured.

Jones, McVeigh's original attorney, said some of the documents withheld from McVeigh's defense could have affected the death penalty phase of his trial by pointing to other, unpunished conspirators.

As for Elohim City, Jones added, "I think Tim was there. I think he knew those people and I think some helped, if not in a specific way, in a general way."

The FBI's scene commander for the Oklahoma City investigation, now retired, said he, too, believes his agency may not have thoroughly investigated possible ties between McVeigh and Elohim City.

"I think you have too many coincidences here that raise questions about whether other people are involved," retired agent Danny Coulson said. "The close associations with Elohim City and the earlier plan to do the same Murrah building all suggest the complicity of other people."