WASHINGTON — Former President Donald Trump has agreed to be interviewed by the FBI as part of an investigation into his attempted assassination in Pennsylvania earlier this month, a special agent said on Monday in disclosing how the gunman prior to the shooting had researched mass attacks and explosive devices.

The expected interview with the 2024 Republican presidential nominee is part of the FBI’s standard protocol to speak with victims during the course of its criminal investigations. The FBI said on Friday that Trump was struck in the ear by a bullet or a fragment of one during the July 13 assassination attempt at a campaign rally in Butler, Pennsylvania.

“We want to get his perspective on what he observed,” said Kevin Rojek, the special agent in charge of the FBI’s Pittsburgh field office. “It is a standard victim interview like we would do for any other victim of crime, under any other circumstance.”

Through more than 450 interviews, the FBI has fleshed out a portrait of the gunman, Thomas Matthew Crooks, that reveals him to be a “highly intelligent” but reclusive 20-year-old whose primary social circle was his family and who maintained few friends and acquaintances throughout his life, Rojek said. Even in online gaming platforms that Crooks visited, his interactions with peers appeared to have been minimal, the FBI said.

His parents have been “extremely cooperative,” with the investigation, Rojek said. They have said they had no advance knowledge of the shooting, a statement the FBI considers credible.

The FBI has not uncovered a motive as to why he chose to target Trump, but investigators believe the shooting was the result of extensive planning, including the purchase under an alias in recent months of chemical precursors that investigators believe were used to create the explosive devices found in his car and his home, and the deployment of a drone about 200 yards from the rally site in the hours before the event in an apparent act of surveillance.

The day before the shooting, the FBI says, Crooks visited a local shooting range and practiced with the gun that would be used in the attack.

After the shooting, authorities found two explosive devices in Crooks’ car and a third in his room at home. The devices recovered from the car — consisting of ammunition boxes filled with explosive material with wires, receivers and ignition devices — were capable of exploding but did not because the receivers were in the “off” position, Rojek said. How much damage they could have done is unclear.

The FBI has said that Crooks had shown an online interest in prominent public figures, searching online for information about individuals including President Joe Biden. In addition, Rojek said, Crooks looked up information about mass shootings, improvised explosive devices, power plants and the attempted assassination in May of Slovakia’s populist Prime Minister Robert Fico.