WASHINGTON— FBI Director Christopher Wray is set to testify Wednesday about the bureau's investigation into the attempted assassination of former President Donald Trump , with lawmakers at a congressional hearing likely to press him for fresh details about the gunman's motive and background.

The hearing before the House Judiciary Committee will represent Wray's most detailed comments to date about a shooting that has again thrust the FBI into the political maelstrom as agents continue to investigate the 20-year-old gunman, Thomas Matthew Crooks , and the most serious attempt to assassinate a president or presidential candidate since President Ronald Reagan was shot in 1981.

The hearing had been scheduled well before the July 13 shooting as part of the committee's routine oversight of the FBI and Justice Department, and though lawmakers may touch on a broad array of topics, questions about the shooting are expected to dominate the session.

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. Though the FBI has avoided the same level of scrutiny directed at the Secret Service over security lapses that preceded the shooting, culminating Tuesday in the resignation of Director Kimberly Cheatle , Wray is likely to be questioned by lawmakers skeptical of the bureau's assessment that Crooks left behind no obvious ideological motive that could explain his actions.

The FBI has said that it is investigating the Butler Farm Show grounds 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 he said pierced the upper part of his right ear.

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

A law enforcement official told The Associated Press last week that Crooks had also flown a drone above the rally site before the event in an apparent effort to scope out the scene in advance.