WASHINGTON (NewsNation Now) — The U.S. Capitol Police officer killed in an attack outside the Capitol last week does not appear to have been stabbed, slashed, or shot, a police official told The Associated Press on Monday.

Officer William “Billy” Evans, an 18-year veteran of the force, died Friday after a driver rammed his car into a barricade near the Capitol. The driver, identified as 25-year-old Noah Green, crashed into two officers and the barrier, then exited the car armed with a knife and lunged at the officers before police fatally shot him, authorities said.

In the chaotic moments after the attack, law enforcement officials initially believed the suspect, who was seen on surveillance video lunging at the officers with a knife, may have stabbed Evans, but that was not the case. Rumors also had swirled around fears that Evans may have been struck by friendly fire when police started shooting at the suspect.

The investigation remains ongoing, but there is no indication that Evans was stabbed, slashed, or shot, a U.S. Capitol Police official told the AP. The official could not discuss details of the investigation publicly and spoke to the AP on the condition of anonymity.

Video of the Friday afternoon attack shows the driver emerging from the crashed car with a knife in his hand and advancing toward the officers, Capitol Police acting Chief Yogananda Pittman said.

Investigators are increasingly focused on Green’s mental health as they work to identify any motive for the attack, a U.S. official briefed on the investigation told the AP. Investigators have learned the suspect had been suffering from delusions, paranoia, and suicidal thoughts, according to the official, who was not authorized to speak publicly about an ongoing matter and spoke to the AP on the condition of anonymity.

In online posts since removed, Green described being under government thought control and said he was being watched. He described himself as a follower of the Nation of Islam and its longtime leader, Louis Farrakhan, and spoke of going through a difficult time when he leaned on his faith. Some of the messages were captured by the group SITE, which tracks online activity.