MONUMENT, Colo. (AP) — In the weeks before Colorado prison director Tom Clements was shot dead after answering his front door, he carried out a variety of functions including requesting execution chemicals and speaking to legislators about security issues.

It's unknown what role Clements' job might have played in the shooting Tuesday night, but investigators said they aren't ruling out any possible motives, including whether it was random or a work-related attack.

El Paso County Sheriff's Lt. Jeff Kramer tells The Denver Post authorities are looking for a late-model car, possibly a Lincoln or a Cadillac, that a neighbor spotted outside Clements' home around the time of the shooting.