The 1995 bombing of the Oklahoma City federal building—at the time the worst peacetime atrocity committed on U.S. soil, with 168 dead and hundreds more injured—has been largely overshadowed by the destruction of the World Trade Center and all that has followed. But the storyline is nevertheless unnervingly familiar.

Like the failure to prevent 9/11, this is a case of the federal government first failing to recognize or act on crucial warning signs and then claiming there were no warning signs at all. It’s about coming up with a plausible cover story and sticking to it, no matter what. In contrast to the most glaring failures of the Bush administration, though, the government’s bluff on Oklahoma City has gone largely uncalled. Timothy McVeigh, the alleged mastermind, was sentenced to death and executed, while Terry Nichols, supposedly his only accomplice, is serving a life sentence. And that, for most people, has been the end of the story. Only the dogged persistence of a handful of amateur investigators, academics, journalists and lawyers has revealed more uncomfortable truths about the bombing and who might have committed it. Thanks to a flurry of Freedom of Information and other lawsuits, the FBI’s own paperwork is beginning to seriously contradict the official version of what happened. And more is being revealed all the time.

We now know, from court records and official documents, that at least two undercover operatives were gathering information on Timothy McVeigh and a group of like-minded white supremacists in the early spring of 1995, one of whom gave her government handlers specific information about a plan to blow up the Alfred P. Murrah Federal Building in Oklahoma City.

We know that, after the bombing, the government expended considerable energy trying to track down a John Doe 2 and other possible accomplices of McVeigh and Terry Nichols—the “others unknown” cited in the federal indictment—before abruptly changing tack nine months later and insisting that McVeigh was the lone mastermind behind the attack and, eventually, that no one else other than Nichols had been involved.

And we know that, as the lone-bomber theory has come under increasingly skeptical scrutiny in recent years, the FBI and other federal agencies have expended considerable energy blocking access to their investigative paper trail. When one of the government informants from the spring of 1995 went public about her role, she found herself prosecuted—unsuccessfully—for allegedly harboring her own bomb plots; she has since gone to ground, too afraid to say more. At least one key government official, the state medical examiner in Oklahoma City, has indicated he was not given key information he needed to do his job. And one of the senior FBI agents involved in the early stages of the bombing probe now believes that enough new evidence has come to the surface from the files of his own agency to warrant a new federal grand jury investigation.

Perhaps most unnerving is the trail of dead bodies that has turned up over the past decade under less than transparent circumstances. A neo-Nazi bank robber called Richard Guthrie, one of the leading John Doe 2 candidates—though never publicly identified as such—was found hanging in a prison cell in July 1996. Kenney Trentadue, a man who looked very much like Guthrie, right down to a snake-motif tattoo on one arm, and appears to have been mistaken for him when he was picked up on a parole violation on the Mexican border in the summer of 1995, wound up bloodied and traumatized from head to toe in his cell at a federal detention facility in Oklahoma City. The feds claimed he hanged himself. An inmate who later came forward and claimed he witnessed Trentadue being beaten to death by his interrogators was himself found hanging in a federal prison cell in 2000.

The person who has done most of the recent work in unmasking the mysteries of Oklahoma City is Kenney Trentadue’s brother Jesse, a Salt Lake City lawyer who has not only fought to have his brother’s death recognized as murder, not suicide, but is also suing the FBI to release a trove of documents that might shed light on the links among McVeigh, Guthrie and a group of Guthrie’s associates widely suspected—at least outside the confines of the Justice Department—of being McVeigh’s bombing accomplices.

Jesse Trentadue has been all over the federal government like a bad case of lice ever since the authorities at the Federal Transfer Center in Oklahoma City unsuccessfully tried to arrange for Kenney’s battered body to be cremated before the family had had a chance to look at it or even learn what kind of injuries he had sustained. He not only insisted on the family taking receipt of the body, he has also raised question after question about the government’s credibility. Jesse has gotten a prison guard to admit under oath that he lied when he testified about seeing Kenney hanging by a bedsheet, gotten the authorities to admit they never told the medical examiner’s office that someone else’s blood was found in Kenney’s cell, and cast compelling doubt on the suicide note Kenney supposedly scrawled in pencil on his cell wall saying he had lost his mind.

Over the years, as the Kenney Trentadue case has become increasingly intertwined with the Oklahoma City bombing case, Jesse Trentadue has won some key allies in both the federal prison bureaucracy and law enforcement. Just over a year ago, a former FBI agent gave him two heavily redacted agency teletypes connecting some of the dots between Richard Guthrie and McVeigh. Trentadue took the documents to federal court to demand unredacted versions, along with any other documents that might shed light on the Guthrie-McVeigh connection [legal briefing]. The legal process is grinding on, but Trentadue has already obtained one key ruling in his favor from U.S. District Judge Dale Kimball and squeezed more than 100 pages of (even more heavily) redacted documents out of the FBI.

Even in redacted form, these documents prove for the first time that FBI investigators were pursuing links between the Oklahoma City bombing and a series of 22 bank robberies carried out across the Midwest in 1993-1995 by a neo-Nazi group calling itself the Aryan Republican Army. Guthrie was a member of the ARA. So too were two members of a skinhead band from Philadelphia, Scott Stedeford and Kevin McCarthy, as well as an old friend of Guthrie’s, Pete Langan, the brains behind the gang who also, curiously, happened to be a closet transvestite with a penchant for shaving his pubic hair and painting his toenails pink.

All were tried and convicted on robbery charges only. But it’s now clear the feds thought they were involved in a whole lot more.

The first teletype, from January 1996, puts BOMBROB, the FBI’s code word for the bank robbery investigation, under the general heading OKBOMB, its name for the bombing investigation. The second teletype, from August 1996, spells out what the ARA was suspected of planning with the tens of thousands of dollars it stole from the banks. In the subject line, the ARA members’ names are grouped along with the topic “Domestic Security/Terrorism.” The “threatened harm,” it says, included political assassination, genocide and bombings. Guthrie and another member of the gang are reported to have admitted giving someone—the name is blacked out—part of the bank robbery loot.

It is already widely suspected that the financing for the Oklahoma City bomb came from the ARA, and indeed that McVeigh was an occasional participant in the bank robberies. McVeigh once told his sister Jennifer that money he passed on to her had come from a bank heist. Does this document show that the FBI had evidence cementing the link between the ARA and McVeigh?

For a certain answer to that, we will have to wait a little longer. Judge Kimball has seen unredacted versions of all the released FBI teletypes, and is expected to rule imminently on whether to make them public. He has indicated fairly strongly that he will, having ruled last May that “the public’s interest in knowing the information [in the teletypes] outweighs the interest of the [named] individuals in keeping such information confidential.”

His ruling could, if it goes in Trentadue’s favor, finally blow the cover of the government’s version of the Oklahoma City bombing. The McVeigh-as-lone-mastermind theory was certainly useful in securing a conviction and death sentence against McVeigh—something that was far from a foregone conclusion at the time of his trial. But that does not mean the government necessarily believes that it is the whole truth; the involvement of McVeigh and Nichols may, rather, have been all that the feds were in a position to prove beyond a reasonable doubt.

Several things about the lone-mastermind theory have never mind sense. The official version does not explain how McVeigh and Nichols could have successfully built the huge fertilizer bomb on their own without any explosives training. (Guthrie, by contrast, had received weapons instruction when he was training, unsuccessfully, to be a Navy SEAL.) It stretches credulity by suggesting that McVeigh drove the fully primed bomb more than 300 miles from Kansas to Oklahoma City—something that ordnance experts say would have carried a high probability of premature detonation. (An alternative theory holds that McVeigh and his accomplices assembled the bomb in Oklahoma City on the morning of the attack.) It cannot explain how every single eyewitness who saw McVeigh as he made his final preparations for the attack saw him with someone else (and not Terry Nichols, either). And it does not account for the financing of the operation: McVeigh was jobless and broke from 1992 on, and yet he spent months shortly before the bombing frantically crisscrossing the country, staying in motels and making several sizable purchases. He paid cash for everything.

If McVeigh did have accomplices, then one place he might have found them was a white supremacist religious compound in rural Oklahoma called Elohim City. The feds were deeply suspicious of Elohim City, seeing it in the early spring of 1995 as potentially another Waco. Its residents included the notorious White Aryan Resistance leader Dennis Mahon, a shady German called Andreas Strassmeir and an occasional ARA member called Michael Brescia. Its visitors included other ARA members and McVeigh, going under the pseudonym Tim Tuttle.

It later emerged that Mahon’s girlfriend, Carol Howe, was an informant for the ATF, the Bureau of Alcohol, Tobacco and Firearms. She was the one who heard plans being hatched—by Mahon and Strassmeir—to blow up a government building, accompanied Elohim City residents on one of three reconnaissance trips to Oklahoma City, and reported seeing McVeigh on the premises. We also know, from evidence that emerged during the pretrial discovery process, that McVeigh called Elohim City two weeks before the bombing and asked to speak to Strassmeir.

The January 1996 FBI teletype made public by Jesse Trentadue adds two intriguing details to this. One is that McVeigh, when he made his phone call, “was believed to have been attempting to recruit a second conspirator to assist in the OKBOMB attack.” And the other is that there was a second informant at Elohim City, working on behalf of the Southern Poverty Law Center, the Alabama-based civil rights organization whose lead lawyer, Morris Dees, has been the scourge of racists and neo-Nazis from one end of the country to the other.

The teletype says the Southern Poverty Law Center informant was at Elohim City two days before the bombing when someone—the name is redacted—put in a phone call to the compound. If true, this is an incendiary revelation, because it suggests that the center knew far more about the Oklahoma City bombing than it let on in its immediate aftermath. In an e-mail he wrote to Jesse Trentadue in January 2005, Mark Potok, who edits the center’s Intelligence Report, flatly denied that the SPLC had an informant, “or anyone else,” at Elohim City. Two years earlier, however, Morris Dees, when asked at a meeting at Southeastern Oklahoma State University whether his organization had had any inside source at Elohim City, made no such denial. Rather, he dodged the question, acknowledging that his organization worked closely with the FBI and other federal agencies but omitting any precise details.

“We did notify the FBI and Janet Reno six months before the Oklahoma bombing that we had strong information that there was going to be a serious domestic terrorism strike,” Dees added. “Within minutes after it [the Murrah Building bombing] hit the news … we called the criminal division of the FBI and said ‘quit looking at Muslim businessmen who visit Oklahoma, you got to be looking at people involved in this Patriot movement.’ ”

We still have no clear idea of who knew what about the bombing, when they learned it, what attempts, if any, were made to prevent the calamity and why any such efforts failed. What we do know, however, is that the government had a lot more information than it was willing to admit publicly—or even to turn over to the defense teams in the various bombing trials that have taken place since 1997.

One trove of hitherto unseen FBI documents cropped up on the eve of Timothy McVeigh’s execution in 2001, delaying his death at the federal death row facility in Terre Haute, Ind., by almost a month. More were leaked to John Solomon, a Washington-based Associated Press reporter, in 2004—including a Secret Service file containing the extraordinary revelation that government agents had access to security videotapes of the Murrah Building in which “the suspects” (more than one) are seen exiting the Ryder truck containing the bomb three minutes before the explosion.

When Terry Nichols was retried on state murder charges in Oklahoma that same year—in an ultimately unsuccessful attempt by prosecutors to get him sentenced to death—the defense team tried to use the Solomon documents as exculpatory evidence for their client on the basis that the more others were involved, the less significant Nichols’ own role would appear to have been. They also made a passionate case that Nichols had been denied a fair trial because the FBI and other agencies had improperly concealed relevant evidence.

The judge in the Oklahoma case, Steven Taylor, refused to grant them satisfaction on that front, saying he simply did not believe the official documents stating that the government had access to security video footage of the Murrah Building. As for any link to the ARA bank robbery gang, he called it a “dry hole.” “There is absolutely no evidence of any overt act by the bank robbers in bombing the Murrah Building,” Judge Taylor insisted, “nothing at all to link the bank robbers to the crime that is being tried before this court.”

That, though, was before Jesse Trentadue came forward with his own stash of official documents. Trentadue is an undeniably colorful character, filling his legal briefs with trenchant statements about the federal government’s iniquities and writing taunting e-mails to Robert Mueller, the FBI director, and others whenever he feels he has won a little victory over them. Last May, when Judge Kimball issued a ruling ordering the FBI to produce every document Trentadue had requested, the subject line of his e-mail to Mueller read: OH MY GOSH DARN BIGGEST FRIGGIN’ HECK!!! “After you read [the judge’s] order,” he wrote, “you are going to need a case of Preparation H!”

If Trentadue is unorthodox in his approach, he is nevertheless effective. In 2001, he secured $1.1 million in damages from the Justice Department for the emotional distress his family suffered over his brother’s suspicious death. That judgment has since been upheld on appeal, although the amount is still being litigated. Over the past year, his assault on the FBI has been equally dogged. When he first made a request for a copy of the January 1996 teletype, the FBI told him it did not exist. When he followed up that request with his own redacted copy of the teletype, along with a declaration from a former FBI special agent giving very specific information on where it was likely to be filed based on information on the teletype itself, the FBI said it had conducted a computer search for the terms Trentadue had requested and come up empty. Such a search, the FBI contended, was all that was required of the agency under the Freedom of Information Act.

Judge Kimball vigorously disagreed. “The court finds that the FBI’s search was not reasonably calculated to discovery [sic] the requested documents,” he wrote in his order last May. The FBI then announced it had 340 relevant documents in its possession and promised to release them all as ordered. When push came to shove, however, the number of documents it actually produced near the end of July was just 25; all were so heavily redacted that in places whole paragraphs were whited out and no significant new information could be gleaned from any of them. “The 340 number,” the FBI explained, “… included numerous multiple matches that actually identified the same document.” Oddly, the batch of 25 documents itself contained multiple versions of the same files; once the duplicates and draft versions were removed, the number of new documents numbered just 17.

Once again, Judge Kimball was unimpressed and ordered the FBI to give him unredacted copies of everything to examine in camera so he could decide for himself whether there was any valid reason to keep the redacted parts secret. At first the FBI resisted vigorously, going so far as to announce the day after Kimball’s new order that it had reopened the Oklahoma City bombing investigation and that it was therefore no longer obliged to respond to any related FOIA request. In the end, though, the FBI produced the documents as ordered, and Kimball conducted his examination of them behind closed doors last November. His decision on their publication is still pending.

The full lessons from all this remain to be learned, in part because we are very far from getting to the bottom of the mystery. But it’s clear that the intelligence failures and institutional coverups we have seen in the wake of the Sept. 11 attacks and the Iraq war are part of a historical pattern. The FBI, in common with other federal agencies, is interested in defending its own bureaucratic interests first and establishing the truth only a distant second. It is prepared to go to extraordinary lengths to avoid having to admit mistakes, even if that means allowing people suspected of posing a significant threat to public safety to go free. Dennis Mahon, who is banned from travel to Britain and other countries because of his political activities, has never been seriously troubled by the Oklahoma City bomb investigators. Andreas Strassmeir was allowed to leave the United States and return to Germany in early 1996 even though it was clear at the time that he had had contact with McVeigh immediately before the bombing and might, at the very least, have made an important witness. Several of the ARA bank robbers, meanwhile, have completed their sentences and are now free.

Even if the FBI has valid reasons for thinking that a broader prosecution of McVeigh’s accomplices could not stand up in court—because the evidence is lacking, or because the case might have to be built on the testimony of neo-Nazis and convicted bank robbers—there is no excuse not to be more forthcoming about what the agency knows, and never mind whose pride gets hurt in the process. America deserves to be told everything possible about the Oklahoma City bombing, just as it deserves to be told everything about 9/11. That includes the full factual record of the crime itself, the conduct of the investigation, the leads that could not be solidified and, yes, the false trails and the screw-ups. In an ideal world, Congress or the FBI itself would be the guarantor of full disclosure. As it is, we have to rely on dogged individuals like Jesse Trentadue to squeeze the information out drop by drop.