WASHINGTON (AP) — 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 their criminal investigations. The FBI said on Friday that Trump was struck 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 circumstances.”

Through roughly 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.

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 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 use of a drone about 200 yards (180 meters) from the rally site in the hours before the event.

In addition, Rojek said, Crooks looked online for information about mass shootings, improvised explosive devices, power plants and the attempted assassination in May of Slovakia’s populist Prime Minister Robert Fico.

The FBI has said that on July 6, the day Crooks registered to attend the Trump rally, he googled: “How far away was Oswald from Kennedy?” That’s a reference to Lee Harvey Oswald, the shooter who killed President John F. Kennedy from a sniper’s perch in Dallas on Nov. 22, 1963.

Crooks’ parents have been “extremely cooperative” with investigators, Rojek said, and the extensive planning that preceded the shooting was done online. The parents have said they had no knowledge of Crooks’ plans, and investigators have no reason to doubt that, the FBI said.