Eight months after an on-campus shooting killed University of Arizona Professor Thomas Meixner, police reports just released show an unlocked door made it easier for the accused gunman to reach Doctor Meixner.

UA has promised to improve security in the aftermath of the killing. Now police reports indicate some security already in place was bypassed.

Expelled graduate student Murad Dervish is charged with murder in the case. He had been expelled and barred from campus after an alleged series of threats towards faculty at atmospheric sciences.

UA Police reports say on the day of the shooting, people in the building recognized Dervish right away.

They called 911. By 2:04pm police cars were on the way using lights and sirens. But by 2:05 officers heard radio calls that someone was shot.

One officers report described the door leading to where Meixner was as a door where youd have to punch in a code to enter. The code had been changed after Dervish was expelled, but the door was propped open to avoid sharing the code with students.

One witness said he heard one or two loud bangs, and saw Dervish trying to force his way in. The witness saw Meixner had blood on his shirt. He says Meixner tried to stop Dervish from getting in but Dervish overpowered him and fired at least three more shots.

UA has promised a series of security upgrades since the killing. They include more classroom locks and keycard access to buildings.

The report offered more detail on a missed opportunity already reported.

About a week before the killing UA police say Dervish, who was barred from campus, came to the UA Police building and asked an officer to check records to see if his new car was reported as stolen.

The officer said he did not know Dervish had been accused of threats and forbidden from campus.

Soon after, another officer who did know Dervish history asked if the officer who talked with Dervish was OK. We did not find any reference to officers trying to catch up to Dervish soon after his visit to the police department.