FBI Director James Comey said the agency began investigating the Jan. 7 shooting of Officer Jesse Hartnett as a terrorist attack almost immediately after Edward Archer of Yeadon confessed, telling authorities he was "following Allah" and that he pledged his allegiance to the Islamic State.
"We are investigating that attack as a terrorist attack," said Comey, who spoke in Philadelphia and limited his comments due to the ongoing investigation. "We are working hard to understand motives ... and whether there might be anyone else involved."
Archer is charged with attempted murder but hasn't entered a plea and is being held without bail. A preliminary hearing is scheduled for Jan. 25. A lawyer recently assigned to defend Archer has declined to comment on the case.
Authorities say Archer, 30, opened fire on Hartnett's marked cruiser, firing more than a dozen shots at point-blank range. After being hit three times in the arm, Hartnett was able to get out of the car, return fire and hit Archer in the buttocks. Archer was apprehended about a block away, according to police.
Hartnett, 33, remains hospitalized and will require multiple surgeries for his injuries. Police Commissioner Richard Ross said Hartnett's arm is "basically destroyed" from the shooting. Comey visited briefly with the officer during his visit.
Hours after the ambush, police said Archer told authorities he believed the police department defends laws that are contrary to the teachings of the Quran. His mother told The Philadelphia Inquirer he had been hearing voices. Comey declined to comment on Archer's mental state.
Archer's remarks to police triggered the FBI's probe into the shooting as potential terrorism.
Comey said the Islamic State group has "for many months now, been trying to motivate people to kill police officers and military service members."
Local and federal investigators are investigating Archer's possible outside ties to terrorism, including whether and how he may have been radicalized. The FBI believes Archer traveled to Saudi Arabia in 2011 and to Egypt in 2012 and is probing the purpose of those trips.
Comey declined to say whether Archer had been radicalized.
Imam Asim Abdur Rashid of the Masjid Mujahideen told The Philadelphia Inquirer that Archer was a frequent member at the mosque and traveled to Saudi Arabia for the Hajj.
Philadelphia police also are investigating a tip received last week from a woman claiming Archer "had an affiliation to a group with radical beliefs."