Investigators were looking for connections to other violent crimes as well.

Police said the car believed to have been used in the attack on the sergeant was found parked in the garage at the Four Seasons Hotel on the downtown riverfront. Sources said a woman there told police that Bush asked her, a stranger, for a cigarette, and then for a ride.

Undercover officers with an FBI task force noticed the woman’s car in an alley near the intersection of Smiley and Leola avenues about 12:45 a.m. and decided to check it out — without knowing for sure that the suspect in the sergeant’s shooting was inside, the sources said.

Bush jumped from the car and started shooting at the officers, who returned fire, officials said. Nobody else was hurt.

It was a St. Charles County officer working on the task force who killed Bush with an AR-15 rifle, the sources said. Task force members are allowed to use such weapons.

The sources said the woman was not involved in the crimes, and that Bush was believed to have been alone when he ambushed the officer. Her information led officers to search the parking garage, where they found the car believed to have been used in the shooting.

Community honors wounded officer