The FBI has been ordered to investigate allegations that claim the agency intimidated a witness and compelled him not to testify at a recent trial over evidence related to the Oklahoma City bombing.

According to theSalt Lake Tribune, US District Judge Clark Waddoups scheduled a November 13th hearing on the matter, in which Utah attorney Jesse Trentadue accused the FBI of threatening to eliminate a former undercover agent’s health benefits if he took the stand. The former agent reportedly knew convicted bomber Timothy McVeigh.

The core of the issue is that Trentadue claims the FBI has surveillance video revealing McVeigh carrying out the Oklahoma City bombing with an accomplice. The FBI adamantly denies that such video exists, and the government has insisted repeatedly that McVeigh acted alone in the event that killed 168 people.

The witness involved in this whole situation, John Matthews, was scheduled to testify regarding this alleged video in July, but withdrew at the last minute. Trentadue – as well as a freelance journalist named Roger Charles – stated that when he spoke with Matthews about his absence, the former agent told them the FBI threatened him.

“He was told he should take a vacation and that if he did testify he should suffer from a case of the ‘I don’t remembers,'” Trentadue told the judge back in July, as quoted by local Fox 13 News.

FBI attorney Kathryn Wyer told Waddoups on Monday that Trentadue’s allegations have no basis in reality, and that they are “another one of [his] conspiracy theories.” She said the agency did not present more evidence in its favor because there is no connection between the FBI and the decision to not testify. She added that the only time agents were in contact with Matthews was when he called the bureau himself to declare his decision to withdraw.

Wyer argued that the agent who took Matthews’ call dealt with him as they would have any other person, and that the individual should not be brought in to speak. However, the judge disagreed.

“The proceeding is going to document whether or not there was any inappropriate contact with Mr. (John) Matthews,” Waddoups said, as quoted by Fox 13. “No one is being accused at this point other than the question has been raised. He’s being given the opportunity to answer that.”

"If all of this is nonsense, let's bring this in and put an end to it," he added, according to the Associated Press.

These allegations come as part of a larger trial, in which Trentadue is suing the FBI to gain access to the alleged video that shows McVeigh acting with another person. He has cited various documents that suggest such a video exists, namely one by a Secret Service agent that describes a security video showing more than one person exiting the rental truck McVeigh was in minutes before the bomb went off.

As noted by the Salt Lake Tribune, this video was mentioned in a 2004 article by the Associated Press, but the article also states that the government claims it does not own video of the bombing scene in the lead-up to the explosion – and that it never had such footage at all.

The FBI says it has looked through its archives extensively, but that no such video is there to be found – nor is any of the evidence Trentadue is looking for. Trentadue is asking the judge to allow him to personally look through the FBI’s archives.

Trentadue’s search for this mystery video is personal. According to the New York Daily News, the lawyer’s brother, Kenneth Trentadue, was taken into the FBI’s custody in the months following the bombing. Kenneth reportedly looked extremely similar to a description given by witnesses regarding a second bombing suspect, dubbed “John Doe No. 2,” though no such suspect was ever pinpointed.

Kenneth, however, ended up dying in a federal holding cell, an incident that was labeled a suicide by state and federal officials. The Trentadue family disagrees, arguing that law enforcement strangled him to death during an interrogation that spiraled out of control.

Jesse Trentadue argues that this alleged video showcasing an accomplice would explain why his brother was taken into custody, and lend credence to his belief that he was killed by law enforcement.

“I did not start out to solve the Oklahoma City bombing, I started out for justice for my brother’s murder,” Trentadue said in July to the Daily News. “But along the way, every path I took, every lead I got, took me to the bombing.”