The executive director of Colorado’s department of corrections was shot dead by an unknown gunman at his home Tuesday night, apparently when he answered a ring at his front door, according to NBC News.  The motive behind the attack is unclear, as is the identity of Tom Clements’ shooter.

No one else in the house was injured.

Investigators canvassed the wooded area around Clements residence with the help of canine units, but no suspects have been identified, the article says. Whether or not his position as director of the Department of Corrections played a role in his death remains under investigation as well.