The remains of Thomas Matthew Crooks, who tried to kill Republican presidential candidate Donald Trump last month, were released to his family for cremation in what appeared to be a cover-up, Congressman Clay Higgins has said.

Crooks was killed by the US Secret Service on July 13 after he opened fire on Trump during his rally in Butler, Pennsylvania. He managed to injure Trump and two rally-goers, while killing a third.

Higgins is a Louisiana Republican with background in law enforcement, and a member of the congressional Task Force established to investigate the attempted assassination. He traveled to Butler earlier this month to examine the crime scene. His report on the trip was made public on Thursday.

“My effort to examine Crooks’ body on Monday, August 5, caused quite a stir and revealed a disturbing fact,” Higgins wrote in the report. “The FBI released the body for cremation 10 days after J13. On J23, Crooks was gone. Nobody knew this until Monday, August 5, including the County Coroner, law enforcement, Sheriff, etc.”

Higgins noted that the county coroner “would have never released Crooks’ body to the family for cremation or burial without specific permission from the FBI.”

The coroner’s report and the autopsy report were not ready as of August 5, and without the body there was no way to verify their accuracy, Higgins noted. Such actions by the FBI “can only be described by any reasonable man as an obstruction to any following investigative effort,” he wrote.

Higgins was in Butler for three days and spent about 20 hours investigating the crime scene. According to his findings, Crooks fired eight shots from the roof of a building overlooking the fairgrounds where Trump spoke. The ninth shot came from a Butler SWAT operator and struck Crooks’ rifle, while the tenth shot from a Secret Service sniper killed him.

The FBI reportedly has the casings from the roof, but they “released the crime scene” after just three days and cleaned up the blood and other “biological evidence,” according to the report.

Crooks did not use a ladder to climb the roof, but an air conditioning unit. He somehow knew to take a position that minimized his exposure to Secret Service snipers, Higgins wrote, noting that it is not usual practice to assign counter-snipers to former presidents.

“I have not yet investigated Crooks’ origins, how he came to be a shooter, how he manufactured a remote trigger bomb, etc. I have not reviewed the harvested evidence, nor have I examined his home, his vehicle, spoken with his family, his neighbors, his classmates, examined his computer, his emails, or his closet,” Higgins wrote, vowing that he intends to do so.