This photo provided by the Virginia State Police shows Ross Truett Ashley, age 22. (AP)

“We’re still working toward establishing and identifying a motive,” said Corinne Geller, a spokeswman for the Virginia State Police.

Ross T. Ashley, 22, bought the .40-caliber, semi-automatic handgun in January at a licensed Virginia dealer, police said. They declined to name the outlet.

The part-time student at Radford University approached Officer Deriek Crouse last Thursday and shot him as he sat in an unmarked patrol car on the Virginia Tech campus, police said. Ashley fled the scene and shot himself a short-time later. The incident dredged up memories of the 2007 rampage in which student Seung Hui Cho killed 32 people and himself.

Police said Tuesday they still have not found a connection between Ashley and Crouse, despite spending the weekend and the first part of the week interviewing Ashley’s friends and family.

Police have also been reviewing surveillance video from on and off campus. Some of the footage shows Ashley visited a retail store in Blacksburg last Wednesday, the same day he stole a car from a real estate office in Radford. Police declined to name the Blacksburg store.

Investigators have also executed search warrants, but they remain under seal. Police released a fresh timeline of the events leading up to the shootings (all times are approximate):

12/7/11 - 11:25 a.m. – At gunpoint, Ashley steals a 2011 white Mercedes SUV from Gilbert Real Estate in the 600 block of Calhoun Street in the City of Radford.

 12/7/11 - 12:11 p.m. – City of Radford Police issue multi-state teletype message to law enforcement for a “Be on the Lookout” for the stolen Mercedes SUV.

 12/7/11 – Later that afternoon, surveillance video places Ashley inside a Town of Blacksburg retailer. This video was not discovered by investigators until Thursday (Dec. 8) — when they were conducting their investigation into the murder-suicide.

12/8/11 – 9:30 a.m. — The Virginia Tech Transportation Institute (VTTI) notifies Blacksburg Police of an abandoned vehicle parked on a gravel drive near the VTTI complex. Police immediately respond, confirm the vehicle is the stolen Mercedes SUV and notify Radford Police.

 12/8/11 – 12:15 p.m. –Virginia Tech Police Officer Deriek W. Crouse has stopped a car in the Coliseum parking lot along Washington Street near the intersection of Spring Road. Officer Crouse is seated inside his unmarked patrol car when Ashley approaches the officer and fatally shoots him. Ashley then flees on foot from the scene.

 12/8/11 – 12:45 p.m. -- As law enforcement search the campus for the shooting suspect, a Montgomery County, Va. Deputy Sheriff spots a male pedestrian walking by himself in the “Cage” parking lot along Duck Pond Drive. As the deputy drives towards the man, he momentarily loses sight of him. When the deputy finally reaches the subject, the man is on the ground and deceased from a self-inflicted gunshot wound.

 12/8/11 5:20 p.m. -- Outside of the Greenhouses, police recover a backpack containing a wool cap and pullover worn by Ashley at the time of Officer Crouse’s shooting. At this stage of the investigation, state police investigators have found no connection between Ashley and a handwritten message on the wall of one of the Greenhouses.