The sniper Matthew Crooks searched for details about the murder of the former President John F Kennedy before his own assassination attempt, announced FBI Chief Christopher Wray during an interrogation in Congress on Wednesday.
It is still unclear whether it was a bullet or shrapnel that hit Trump's ear.
On July 6 this year, the 20-year-old Matthew Crooks is said to have googled how far away Lee Harvey Oswald was when he shot dead the then President John F Kennedy, according to Wray.
A week later, Crooks shot at the former President Donald Trump when he spoke at a campaign meeting in Butler in the state of Pennsylvania.
During the interrogation, FBI Chief Wray also stated that Crooks flew a drone over the area where Trump held his campaign meeting just two hours before the deed.
What motive Crooks, who was shot dead by snipers after 30 seconds, had for the shooting is still not established according to the FBI.
In an earlier interrogation in Congress, FBI Chief Wray said that Crooks had previously searched for both Biden and Trump, on which dates Trump would appear, as well as information about the Democrats' convention.
Trump was lightly injured in the ear during the shooting.
When it comes to former President Trump, it is unclear whether it was a bullet or shrapnel that hit his ear, said FBI Chief Wray.
Besides the shooter, one person in the audience died in connection with the incident.