Oklahoma City bombing conspiracy theories

A variety of alternative theories have been proposed regarding the Oklahoma City bombing. These theories reject all, or part of, the official government report. Some of these theories focus on the possibility of additional co-conspirators that were never indicted or additional explosives planted inside the Murrah Federal building. Other theories allege that government employees and officials, including US President Bill Clinton, knew of the impending bombing and intentionally failed to act on that knowledge. Government investigations have been opened at various times to look into the theories.
Overview.
At 9:02 a.m. CST April 19, 1995, a Ryder rental truck containing more than of ammonium nitrate fertilizer, nitromethane, and diesel fuel mixture was detonated in front of the north side of the nine-story Alfred P. Murrah Federal Building. The attack claimed 168 lives and left over 600 people injured.
Shortly after the explosion, Oklahoma State Trooper Charlie Hanger stopped 26-year-old Timothy McVeigh for driving without a license plate and arrested him for that offense and for unlawfully carrying a weapon. Within days, McVeigh's old army friend Terry Nichols was arrested and both men were charged with committing the bombing. Investigators determined that they were sympathizers of a militia movement and that their motive was to retaliate against the government's handling of the Waco and Ruby Ridge incidents (the bombing occurred on the second anniversary of the Waco incident). McVeigh was executed by lethal injection on June 11, 2001 while Nichols was sentenced to life in prison.
Although the indictment against McVeigh and Nichols alleged that they conspired with "others unknown to the grand jury", prosecutors, and later McVeigh himself, said the bombing was solely the work of McVeigh and Nichols. In this scenario, the two obtained fertilizer and other explosive materials over a period of months and then assembled the bomb in Kansas the day prior to its detonation. After assembly, McVeigh allegedly drove the truck alone to Oklahoma City, lit the fuse, and fled in a getaway car he had parked in the area days prior.
Additional conspirators.
Several witnesses reported seeing a second person with McVeigh around the time of the bombing, whom investigators later called "John Doe 2". In 1997, the FBI arrested Michael Brescia, a member of Aryan Republican Army, who resembled an artist's rendering of John Doe 2 based on the eyewitness accounts. However, they later released him, reporting that their investigation had indicated he was not involved with the bombing. One reporter for "The Washington Post" reflected on the fact that a John Doe 2 has never been found: "Maybe he'll (John Doe 2) be captured and convicted someday. If not, he'll remain eternally at large, the one who got away, the mystery man at the center of countless conspiracy theories. It's possible that he never lived. It's likely that he'll never die."
An informant (Carol Howe) for the Department of Alcohol, Tobacco and Firearms who had infiltrated the white supremacist enclave Elohim City, Oklahoma filed a report in January 1995 stating that Andreas Strassmeir, Elohim City's security chief, had spoken about destroying a Federal building and had visited the Murrah building with another man. Two days after the bombing, this informant reminded the ATF of the earlier report and urged investigation into a possible connection to Elohim City. McVeigh is known to have telephoned Elohim City two weeks before the bombing. Jane Graham, a Housing and Urban Development employee at the Murrah building who survived the bombing, later stated that in the days before the bombing she had observed multiple suspicious persons who she suspected may have been involved (such as unfamiliar persons in maintenance or military uniforms), but that her observations were ignored by authorities. Graham later identified one of these men as Andreas Strassmeir of Elohim City.
There are several theories that McVeigh and Nichols had a possible foreign connection or co-conspirators. This was due to the fact that Terry Nichols traveled through the Philippines while terrorist mastermind Ramzi Yousef of the 1993 World Trade Center bombing was planning his Project Bojinka plot in Manila. Ramzi Yousef placed the bomb used in the 1993 World Trade Center bombing inside a rented Ryder van, the same rental company used by McVeigh, indicating a possible foreign link to Al-Qaeda. Other theories link McVeigh with Islamic terrorists, the Japanese government, and German neo-Nazis.
Nichols specifically alluded to other conspirators in 2006 declaration: "There are others who assisted McVeigh whose identifies are unknown to me," but Nichols also identified two "co-conspirators". In addition to unknown persons, Nichols believed Andreas Strassmeir was an agent provocateur, and FBI agent Larry Potts was involved in the bombing plot. Nichols went on to deny any connection to terrorist groups in the Philippines. The FBI did not reply to media requests for comment on Nichols' allegation. 
There has also been speculation that an unmatched leg found at the bombing site may have belonged to an unidentified, additional bomber. It was claimed that this bomber was either in the building when the bombing occurred, or had previously been murdered, and McVeigh had left his body in the back of the Ryder truck to hide it in the explosion.
Additional explosives.
One theory contends there was a cover-up of the existence of additional explosives planted within the Murrah building. The theory focuses on the local news channels reporting the existence of a second and third bomb within the first few hours of the explosion. Theorists point to nearby seismographs that recorded two tremors from the bombing, believing it to indicate two bombs had been used. Experts dispute this, stating that the first tremor was a result of the bomb, while the second tremor was due to the collapse of the building.
Conspiracy theorists say that there are several discrepancies, such as a proposed inconsistency between the observed destruction and the bomb used by McVeigh. Physicist Samuel T. Cohen, known as the primary inventor of the neutron bomb, stated in a letter to an Oklahoma politician that he did not believe a fertilizer bomb was capable of causing the destruction at the Murrah building. Similarly, Air Force Brigadier General Benton K. Partin expressed an opinion that there must have been additional explosive charges inside the Murrah building.
US federal government involvement.
Another theory alleged that President Bill Clinton had either known about the bombing in advance or had approved the bombing. It is also believed that the bombing was done by the government to frame the militia movement or enact antiterrorism legislation while using McVeigh as a scapegoat. Still other theories claim that McVeigh conspired with the CIA in plotting the bombing.
In a 1993 letter to his sister, published by "The New York Times" in 1998, McVeigh claimed that during his time at Fort Bragg he and nine others were recruited into a secret black ops team that smuggled drugs into the United States to fund covert activities and "were to work hand-in-hand with civilian police agencies to "quiet" anyone whom was deemed a "security risk." (We would be gov't-paid assassins!)" In a 2001 declaration Terry Nichols, McVeigh's convicted co-conspirator, also alleged that McVeigh reported in December 1992 how he "had been recruited to carry out undercover missions"Paragraph 10 which initially involved visiting gun shows and making contact with a loose network of anti-government and far-right sympathizers. This undercover activity allegedly escalated to armed robberies and a planned bombing under the direction of FBI agent Larry A. Potts.Paragraph 33 David Paul Hammer, a convicted murderer in the same facility as McVeigh for about two yeas, reported that McVeigh stated similar allegations to him: that McVeigh was an"undercover operative" for the Department of Defense, and that Andreas Strassmeir was a similar operative but with "a different handler" and they had worked together in planning the bombing. 
Filmmaker Bill Bean believes he filmed and briefly spoke to McVeigh on August 3, 1993 while doing location scouting at Camp Grafton in North Dakota. With a handheld camera, Bean filmed and conversed with a self-described parts clerk who was wearing a cap and military fatigues. This event occurred over a year after McVeigh resigned from the Army, and this Bean believes he has proof that McVeigh was still in the military after his supposed resignation. Michael Blomgren, speech pathology professor at the University of Utah, compared the voice of the soldier in Bean's footage to McVeigh's "60 Minutes" interview and thought there as an 86% likelihood they were the same person but Bean notes the US Military and FBI have denied that McVeigh was the man filmed at Camp Grafton.
Investigations.
In 2006, US Congressman Dana Rohrabacher, (Republican, California), said that the Subcommittee on Oversight and Investigations of the U.S. House Committee on International Relations, which he chaired, would investigate whether the Oklahoma City bombers had assistance from foreign sources. On December 28, 2006, when asked about fueling conspiracy theories with his questions and criticism, Rohrabacher told CNN: "There's nothing wrong with adding to a conspiracy theory when there might be a conspiracy, in fact." Among other unresolved questions, Rohrabacher also criticized the FBI for not explaining how Nichols, who did not work steadily, paid for his several trips to the Philippines and had $20,000 cash; for not finding explosives concealed in Nichols's house until a decade after the bombing; for not explaining the "rush to rule out the existence of John Doe Number 2"; and for not thoroughly investigating possible connections between McVeigh and the Aryan Republican Army and Andreas Strassmeir. In March 2007, Danny Coulson, who served as deputy assistant director of FBI at the time of attacks, voiced his concerns and called for reopening of investigation.
On September 28, 2009, Jesse Trentadue, a Salt Lake City attorney, released security tapes that he obtained from the FBI through the Freedom of Information Act that show the Murrah building before and after the blast from four security cameras. The tapes are blank at points before 9:02 am, the time of detonation. Trentadue said that the government's explanation for the missing footage is that the tape was being replaced at the time. Said Trentadue, "Four cameras in four different locations going blank at the same time on the morning of April 19, 1995. There ain't no such thing as a coincidence." Trentadue became interested in the case when his brother, Kenneth Michael Trentadue, died in federal custody, during what Trentadue believes was an interrogation because Kenneth was mistaken for a possible conspirator in the Oklahoma City bombing. In a civil suit, the court determined Trentadue's injuries could have been self-inflicted and rejected the Trentadue family claim that he was murdered. However, the family was awarded $1.1 million for emotional distress on the findings the Bureau of Prisons mismanaged the investigation and aftermath of Trentadue's death.
In November 2014, John R. Schindler, a former professor at the Naval War College and National Security Agency intelligence officer, wrote "It would be good if a serious re-look at OKBOMB’s many unanswered questions were established for the event", because of "the existence of important evidence indicating there’s something we should be talking about". He stated that when he participated in a reexamination by the United States Intelligence Community after the September 11 attacks of possible foreign involvement with recent terrorist attacks, he found "as Rohrabacher’s investigators did a few years later, that the FBI and DoJ had no interest in anyone peeking into the case, which they considered closed, indeed tightly shut. Even in Top Secret channels, avenues were blocked". While cautioning that the bombing "has attracted more than its share of charlatans and self-styled experts, some of whom are eager to pin the bombing on Arabs, Masons, Jews, and perhaps space aliens", Schindler urged a resumption of Rohrabacher's investigation and cited two issues as notable: McVeigh's and Nichols's visits to the Philippines, and the activities of a German national and friend of McVeigh.