The head of Colorado state's prison system was shot and killed at his home, just hours before the governor signed into law on Wednesday a package of gun control measures spurred by a rash of deadly mass shootings in Colorado and elsewhere.
Police said Tom Clements, 58, appointed two years ago as executive director of the Colorado Department of Corrections, was shot on Tuesday night at his home in a secluded wooded area near the picturesque town of Monument, 45 miles south of Denver.
The killing did not appear to be linked to any break-in or robbery attempt, said El Paso County Sheriff's Department Lieutenant Jeff Kramer, but added, "We don't know if the shooting was random."
He said investigators were considering the possibility that Clements' position as head of state prisons might have been a motive behind the attack, and the 31 years he spent in the Missouri Department of Corrections.
Clements' home sits on a street that is "not a major thoroughfare," Kramer said. "There's no reason to turn off onto that road unless you had business there."
Authorities disclosed few additional details on the circumstances of the shooting, but Kramer said that according to a 911 emergency call, Clements was shot after answering the doorbell.
Officials began a search for Clements' assailant on Tuesday night, but as of Wednesday morning they had not identified any suspects, Kramer said.
Governor John Hickenlooper, visibly shaken by news of the shooting, praised Clements as a "great friend to me" and a dedicated administrator.
"He helped define what a public servant is. He did his job quietly, intently, he cared deeply about his staff, his family, his community," the governor said at a news conference.
As previously scheduled on Wednesday morning, Hickenlooper signed legislation to extend background checks on gun buyers -- paid for by applicants -- to private firearms sales and to limit the size of ammunition magazines that may be sold in the state.
The measures were introduced in the Democratic-controlled state Legislature earlier this year and swiftly passed, moving Colorado to the forefront of a national debate over gun violence, which was re-ignited by several mass shootings in 2012. They included massacres of school children in Newtown, Connecticut, and moviegoers in suburban Denver.
A previous loophole in state law that exempted firearms sales at gun shows from background checks was closed following the 1999 Columbine High School massacre in Colorado where two students shot dead a teacher and 12 students before committing suicide.
Columbine had stood as the deadliest public school shooting on record until 20 first-graders and six adults were slain by a gunman last December at the Sandy Hook Elementary School in Newtown.
Five months before the Sandy Hook massacre, a gunman opened fire during the midnight screening of the Batman movie "The Dark Knight Rises" in the Denver suburb of Aurora, killing 12 people and wounding 58 others.
A national assault weapons ban backed by President Barack Obama ran into trouble on Tuesday when Senate Majority Leader Harry Reid acknowledged there was not enough support for it.