The FBI has managed to gain access to the phone of Thomas Matthew Crooks, the bomber at the Donald Trump rally, the bureau said in a statement.
The bureau is analyzing Crooks' electronic devices and has searched his home and car, the FBI said.
Investigators have also conducted "approximately 100 interviews of law enforcement personnel, event participants and other witnesses."
The investigative steps are part of the FBI's initial investigation into Saturday's shooting at a campaign rally for former US President Trump, which it is investigating as an assassination attempt on the former president and domestic terrorism.
Authorities have previously said they believe Crooks acted alone and that they have not yet been able to identify a motive for the shooting.