Updated at 4:20 p.m. ET
MONUMENT, Colorado Colorado's top state prison official was shot and killed when he answered the front door of his house, setting off a hunt for the gunman and raising questions about whether the attack had anything to do with his position.
Authorities are also looking for a dark-colored "boxy" car seen near the house of Tom Clements, 58, when he was shot around 8:30 p.m. Tuesday in Monument, north of Colorado Springs. The vehicle's engine was running and a witness reported seeing one person driving away in the car.
Lt. Jeff Kramer of the El Paso County Sheriff's Office said investigators have not ruled anything out, but the shooting could have been related to Clements' job as executive director of the Colorado Department of Corrections.
"As the director of the Department of Corrections or any similar type position, it could in fact open someone up to be a target of a crime such as this. Although we remain sensitive to that, we also want to make sure that we remain open-minded to other possibilities as well," Kramer said.
The FBI and the Colorado Bureau of Investigation have joined the case, he said.
Clements, 58, was appointed to serve as the head of the DOC by Governor John Hickenlooper in January 2011 after he served for more than three decades in the Missouri Department of Corrections. He oversaw operations of state and private prisons and parole operations.
Hickenlooper, red-eyed and somber at Wednesday's news conference, said he didn't think the killing was part of any larger attack against his cabinet.
In an email to Department of Corrections employees notifying them of the killing, Gov. Hickenlooper said, "I can hardly believe it, let alone write words to describe it. I am so sad. I have never worked with a better person than Tom, and I can't imagine our team without him."
The governor described Clements as "unfailingly kind and thoughtful."
A family member called 911 to report the shooting. Search dogs were called in to comb through a wooded area around Clements' home, and authorities were going house to house trying to find out what neighbors heard and saw.
Clements lived in a wooded neighborhood of large, two-story houses on expansive 2-acre lots dotted with evergreen trees in an area known as the Black Forest. Long driveways connect the homes to narrow, winding roads that thread the hills. Clements' home was out of view, behind a barricade of crime-scene tape in the road.
It would have been simple to find where Clements lived. It took two clicks to get his correct street address through a publicly available internet locator service Wednesday morning. The listing also included his previous home address in Missouri.
While Clements generally kept a low profile, his killing comes a week after Clements denied a Saudi national prisoner's request to be sent to his home country to serve out his sentence.
Homaidan al-Turki was convicted of sexually assaulting a housekeeper and keeping her as a virtual slave. Clements said state law requires sex offenders to undergo treatment while in prison and that al-Turki had declined to participate.
Al-Turki, a well-known member of Denver's Muslim community, was convicted in state court in 2006 of unlawful sexual contact by use of force, theft and extortion and sentenced to 28 years to life in prison. A judge reduced the sentence to eight years to life.
Al-Turki insisted the case was politically motivated. He owned a company that some years ago sold CDs of sermons recorded by Anwar al-Awlaki, killed in a drone strike in Yemen in 2011.
Al-Turki's conviction angered Saudi officials and prompted the U.S. State Department to send Colorado Attorney General John Suthers to Saudi Arabia to meet with King Abdullah, Crown Prince Sultan and al-Turki's family.
After Clements' shooting, someone with the State Department called the Colorado Corrections Department.
Prisons spokeswoman Alison Morgan said she had no details on the call other than to say it wasn't connected to the shooting investigation and may have been a simple courtesy. "They called us because we have a cooperative international program with them," she said.
Attorney Henry Solano, one of al-Turki's attorneys, said he has not been contacted by investigators. He refused to comment on the shooting.
State officials said they have increased security for top Colorado government appointed officials and have increased security at the governor's mansion in the wake of the incident. Officials told KCNC reporter Brian Maass the move was purely precautionary and there was no threat that would make it seem other state leaders were in danger.
Clements is at least the second state prisons chief killed in office. Michael Francke, director of the Oregon Department of Corrections, was stabbed to death outside his office in 1989 in what prosecutors described as a bungled car burglary.
A former Oregon prison inmate, Frank Gable, was found guilty of aggravated murder in 1991 and sentenced to life in prison. He and supporters contend he was wrongly convicted.
Clements' slaying was reminiscent of the 2008 killing of Adams County prosecutor Sean May. His wife was six months pregnant when he was shot and killed as he returned from work to his home in northwest Denver. His killer was never found.
Gov. Hickenlooper ordered flags lowered to half-staff at public buildings until the day after Clements' funeral. Clements is survived by his wife, Lisa, and their two daughters.