Authorities believe the gunman who killed Virginia Tech policeman Deriek W. Crouse acted alone, the Chicago Tribune is reporting. The suspect changed clothes after he fled the scene, and killed himself with a shotgun when he was spotted by another officer.

Corinne Geller, the police spokeswoman for Virginia Tech, has said investigators haven’t found anything connecting the suspect to Crouse. The slain officer was shot in his car in a campus parking lot after pulling the suspect over for a traffic stop.

Gellar added the suspect’s motive is a mystery. While at a press conference, she also said that’s “very much the fundamental part of the investigation right now.”

The gunman wasn’t a student at Virginia Tech, which was the scene of the deadliest gun rampage in modern U.S. history in 2007. Gellar also said investigators are confident they know the gunman’s identity, but they won’t reveal his name, age or hometown until they confirm it and notify his next of kin. Authorities have a video from Crouse’s police car that show the male suspect with a handgun pointed at the car at the time of the shooting.

The shooting occurred the same day Virginia Tech officials were in Washington to fight the federal government fine that they didn’t handle he 2007 massacre properly. Crouse was one of about 50 officers on the campus force, which also includes 20 full- and part-time security guards. He was trained as a crisis intervention officer, as well as a general, firearms and defensive tactics instructor.

Written by: Karen Benardello