Grusch testified during a US government congressional hearing that he believes the government has possession of UAPs, unexplained anomalous phenomena, formerly known as UFOs.
Grusch was one of three witnesses that testified before a House Subcommittee on National Security Border Foreign Affairs hearing on "Unidentified Anomalous Phenomena: Implications on National Security, Public Safety and Government Transparency".
"I was informed, in the course of my official duties, of a multi-decade UAP crash retrieval and reverse-engineering program to which I was denied access."
Grusch also said several times during the hearing that he could not publicly comment on certain information because it is classified.
He also did not specify if the government had in fact "made contact with intelligent extraterrestrials" or if they had obtained any alien life forms from crashed UAPs.
"As I've stated publicly already in my NewsNation [interview] biologics came with some of these recoveries." This is in reference to aired interviews with Debrief and Newsnation, where he alleged that the federal government were hiding evidence of alien craft from Congress. These interviews are what prompted the hearing.
When he was asked if the recoveries were human or non-human, he replied, "Non-human, and that was the assessment of people with direct knowledge on the program I talked to."
"I made the decision, based on the data I collected, to report this information to my superiors and multiple inspectors general, and in effect become a whistleblower."
The Pentagon has denied Grusch's claims.
Defense Department spokeswoman, Sue Gough, released a statement explaining that investigators have not found "any verifiable information to substantiate claims that any programs regarding the possession or reverse-engineering of extraterrestrial materials have existed in the past or exist currently".
Grusch said that he became a 'government whistleblower' after his discovery, and the retaliation that he received after coming forward with his claim.
"It was very brutal and very unfortunate, some of the tactics they used to hurt me both professionally and personally," he said of the retaliation.
Republican congressman, Tim Burchett, who is co-leading this investigation, also claimed that the US is in possession of evidence that suggests there is technology "defies all of our laws of physics", and that alien craft possess technology that could "turn us into a charcoal briquette".
"We're not bringing little green men or flying saucers into the hearing. Sorry to disappoint about half y'all. We're just going to get to the facts," Burchett said.