Thomas Crooks, the shooter who killed one person and injured Republican presidential candidate Donald Trump on July 13, may have possessed a collapsible stock weapon, FBI Director Christopher Wray told lawmakers on Capitol Hill on Wednesday.

Wray stressed to the House's judiciary committee that it wasn't a final conclusion, as FBI agents and other law enforcement officials continue to investigate the shocking event. But it could explain one of the questions yet to be answered: specifically, how Crooks was seen on the ground by some individuals before the shooting in Butler, Pa., but was not viewed in possession of a gun until he climbed his perch on a nearby roof.

"The weapon had a collapsible stock which might explain why it was less easy to observe," he said.

Wray said Trump came into particular focus for the shooter on July 6, at which point he also performed a web search for the distance Lee Harvey Oswald was from president John F. Kennedy in the 1963 assassination in Dallas.

He said Wednesday that initial analysis of a laptop owned by Crooks included some "foreign public figures," without specifying individuals.

WATCH | Secret Service director bows to bipartisan pressure: 

U.S. Secret Service director resigns after failure to stop shooting at Trump rally

U.S. Secret Service director Kimberly Cheatle has reportedly resigned from her post, after a merciless hearing over the agency's failure to stop the attempted assassination of former president and Republican candidate Donald Trump. Read more: https://www.cbc.ca/news/world/kimberly-cheatle-us-secret-service-resigns-trump-assassination-attempt-1.7272229 #Politics #2024election

The FBI has said it is investigating the shooting, which killed one rallygoer and seriously injured two others, as an act of domestic terrorism and an attempted assassination. Trump's campaign said the presumptive GOP nominee was doing "fine" after the shooting, which Trump said pierced the upper part of his right ear.

The furor over the shooting led to bipartisan calls for the resignation of Secret Service Director Kimberly Cheatle, which occurred on Tuesday.

'Crude' explosive devices recovered

While a five-foot ladder was purchased by the shooter, Wray said, it was recovered not at the shooting perch nor in the shooter's vehicle, he added without specifying its location.

Instead, officials believe Crooks used unspecified "mechanical equipment" from the ground and vertical piping on the side of the building to climb atop it.

Wray said eight cartridges were found on the roof after a countersniper fatally shot Crooks.

"He was able to get more rounds off more quickly than he would with other types of weapons," said Wray of the AR-15-style weapon used by Crooks. The gun was purchased by the shooter's father, legally, years earlier.

Officials are still analyzing a drone that Wray said Crooks flew 200 yards (182 metres) away from the stage just a few hours before the early evening shooting. It was recovered from the shooter's vehicle.

The FBI's director said there's no evidence that Crooks had any co-conspirators at this point.

Three "relatively crude" explosive devices were found, he said, two in the shooter's vehicle at Butler and one at the shooter's home in nearby Bethel Park. Wray said Crooks had a transmitter on his person, but that it wasn't clear at this point if they would have resulted in explosions if he had utilized it.

Wray and other senior officials privately briefed members of Congress last week, telling them that Crooks had photos on his phone of Trump, Democratic President Joe Biden and other officials and had looked up the dates for the Democratic National Convention as well as Trump's appearances.

But he stressed that in contrast to other high-profile shooters, Crooks appears to have not left a significant online footprint or engaged extensively in conversations on public forums. He did say that Crooks at times used encrypted messaging apps, without getting into details of those messages.

Wray, as he has done at other congressional committee hearings, condemned harmful rhetoric and a heightened environment for threats, which have been directed at politicians, lawyers and judges and volunteer election officials. Wray himself was the subject of alleged threats, with a Georgia man indicted in that case earlier this month.

New York Democrat Jerry Nadler stressed that dehumanizing and violent rhetoric had often come from Republicans, including Trump himself.

"If you think that this one assassin's bullet was a bolt out of the blue, and not part of a wave of violence that has threatened this nation for years, then you have missed the point," said Nadler.

Despite being appointed by Trump, Wray typically faces antagonistic questions from the Republican-led panel, a reflection of lingering discontent over the FBI's investigation into potential ties between Russia and the 2016 campaign, as well as an FBI search of Trump's Florida estate for classified documents after allegedly defying a subpoena.

Wray, in response to questions from Democrats, said he wasn't familiar with the details of Project 2025, the term for the Heritage Foundation's nearly 1,000-page handbook for the next Republican administration. But he expressed disapproval for any FBI reform that would involve the firing of civil servants for political reasons, or any director directly taking their cues on priorities from a president.