Investigators are working to break into the phone of the man who shot at former President Donald Trump at a Pennsylvania rally on Saturday. The shooting is being probed as an assassination attempt.

The Federal Bureau of Investigation said in a statement that it had obtained the shooter’s phone “for examination.” Officials told reporters in a conference call Sunday, as reported by The New York Times, that agents in Pennsylvania were unable to break into the phone. It’s been shipped to the FBI’s lab in Quantico, VA, where the FBI hopes to get past the phone’s password protection, the Times reported.

Investigators are still looking for insight into the motives of Thomas Matthew Crooks, a 20-year-old from Bethel Park, PA who they identified as the gunman. Kevin Rojek, the FBI special agent in charge in Pittsburgh, told the Times and other outlets that the agency has access to some of Crooks’ text messages, but they haven’t shed much light on his beliefs.