Before Omar Mateen charged into the Pulse nightclub in Orlando and killed 49 people in June 2016, the FBI conducted two so-called assessments, the bureau’s term of art for limited national security investigations that do not require probable cause. In both cases, the bureau determined that Mateen was not a potential terrorist.

During the attack, while barricaded in a bathroom, Mateen suggested to hostage negotiators that he had committed the nightclub massacre in response to U.S. airstrikes in Syria and Iraq, including one that killed senior Islamic State member Abu Wahib.

“You have to tell America to stop bombing Syria and Iraq. They’re killing a lot of innocent people,” Mateen said by phone, shortly before police shot him. “So what am I to do here when my people are getting killed over there?”

After the shooting, then-FBI Director James Comey said federal agents would examine their failures to stop Mateen before he attacked “in an open and honest way and be transparent about it.” The FBI has not disclosed what came of the examination. When The Intercept inquired about it one year after the attack, the FBI answered: “We have no comment.”

A motion filed on Sunday may help explain the FBI’s lack of transparency. In it, lawyers for Mateen’s widow, Noor Salman, who is charged with material support and obstruction of justice in connection with the Pulse attack, say Mateen’s father, Seddique Mateen, worked as an FBI informant for 11 years, up to June 2016, when Mateen attacked the nightclub. The prosecution knew this but sought to hide it, Salman’s lawyers say.

The disclosure is significant because it sheds light on why the FBI may have chosen to close the assessments of Omar Mateen. FBI files provided to Salman’s defense lawyers suggest that agents consulted Mateen’s father, in his capacity as an informant, during the first assessment, raising questions about whether Seddique Mateen helped persuade FBI agents to close out an inquiry that could have prevented the deadly terrorist attack. It’s unclear whether the FBI consulted the elder Mateen during the second assessment as well.

Assessments, intended to provide quick responses to possible security threats, allow FBI agents to investigate people based on nothing more than internal suspicions or vague tips from the public. Though the law does not establish a time limit, the bureau restricts assessments to 60 or 90 days unless agents find information to justify a full investigation.

The FBI launched its first assessment of Omar Mateen in 2013 after he had allegedly boasted to co-workers at G4S, a security company, that he had terrorist connections. The FBI reported that it had closed the investigation after Mateen told agents he made the comment to scare his co-workers, who were reportedly mocking his religion. One year after closing that first assessment, the FBI opened a second, spurred by Mateen’s relationship with Moner Mohammad Abusalha, a Florida man who became the first American suicide bomber in Syria. Mateen and Abusalha attended the same mosque on Florida’s Atlantic coast. The FBI, finding that Mateen’s contact with Abusalha was minimal, closed that assessment as well.

An FBI intelligence report indicates that agents told an unidentified undercover informant that they were investigating Mateen. The informant then “became very upset” that Mateen was under scrutiny, according to the report. Although neither federal prosecutors nor the FBI has confirmed that the unidentified informant in the report was Mateen’s father, defense lawyers for Salman assert that they “can now infer” that Seddique Mateen “played a significant role” in the FBI’s decision to close the assessment and not to pursue a larger investigation or criminal charges against Mateen.

While Mateen’s widow is standing trial for allegedly aiding the Pulse attack and misleading investigators, Seddique Mateen has not faced criminal charges despite a tip to the FBI that he raised money for terrorism in Pakistan, and an ongoing investigation into money transfers he allegedly made to Turkey and Afghanistan.

According to an email from Assistant U.S. Attorney Sara Sweeney to Salman’s lawyers, an anonymous tip indicated that Seddique Mateen, an immigrant from Afghanistan, was trying to raise $50,000 to $100,000 to support an attack against the government of Pakistan. The tip came on November 1, 2012, while Seddique Mateen was working as an FBI informant. After the Pulse shooting, an FBI search of Seddique Mateen’s home uncovered receipts for money transfers to Turkey and Afghanistan between March and June 2016, right before the Pulse shooting. Omar Mateen was researching flights to Turkey at the same time that his father was sending payments there, according to defense lawyers’ summary of FBI evidence.

“Now, the fact that Seddique was sending money to Turkey and Afghanistan indicates the possibility that Omar Mateen was planning to travel to either of those countries to join forces with a terroristic organization,” Fritz Scheller and Charles Swift, Salman’s lawyers, allege in their filing. These facts, they argue, undercut the government’s claim that Salman was aware of plans for and aided her late husband’s terrorist attack.

Defense lawyers have the option to call Seddique Mateen as a witness and ask about his work as an FBI informant. But federal prosecutors have said they do not intend to cross examine the elder Mateen. Sweeney notified the defense that they “will not seek to elicit any of this information from him.”

Salman’s trial continues today. During testimony this morning, FBI Special Agent Juvenal Martin, Seddique Mateen’s FBI handler, admitted that federal agents had considered recruiting the younger Mateen as an informant before he attacked the Orlando nightclub.

A federal judge on Monday rejected Salman’s request for a mistrial in light of the new information. As a policy, the FBI neither confirms nor denies the identity of informants.