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. 
 
 The home of the Clements family in Monument, Colorado. / CBS 
 
 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. 
 
 Colo. prisons chief shot and killed at home 
 
 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. ||||| DENVER — As Colorado’s governor signed a hard-won package of gun control measures on Wednesday, officials across the state were reeling from the seemingly inexplicable shooting death of the state’s prisons chief, who was gunned down at the front door of his home. 
 
 The killing of Tom Clements, a man described by friends and colleagues as a dedicated and thoughtful public servant, left state officials shaken and grasping for answers on Wednesday. State troopers increased security around the State Capitol, and some state workers said Mr. Clements’s death had put them on edge. 
 
 The state police said they had known of no specific threats against Mr. Clements before 8:30 p.m. Tuesday, when someone approached his house in the pine-fringed hills of the town of Monument, near Colorado Springs, and shot him as he answered the door. Into Wednesday night, investigators were still searching for any trace of his killer, but said they had no suspects or motive. 
 
 Officials with the El Paso County Sheriff’s Office said they were looking for a “boxy” two-door car that had been spotted Tuesday night in the neighborhood, its engine running but with nobody inside. 
 
 They said Mr. Clements’s post, overseeing more than 20,000 inmates in Colorado’s prisons and parole system, might have made him a target. 
 
 Among his most prominent recent decisions, he denied a request this month from a prominent Saudi-born prisoner convicted of sexually abusing his housekeeper to serve the duration of his sentence in Saudi Arabia. 
 
 Mr. Clements’s death came just hours before Colorado’s governor, John W. Hickenlooper, signed a bitterly divisive package of gun-control measures into law, capping weeks of tumultuous and emotional debate about gun ownership and violence in a state scarred by two mass shootings. 
 
 The news about Mr. Clements rippled through the Capitol, where lawmakers and crime victims had gathered to watch Mr. Hickenlooper sign the gun bills. Staff members asked one another, “Are you O.K.?” Tearful elected officials hugged and shared memories of Mr. Clements, 58, recalling his dedication in serving Colorado after a career with Missouri’s Department of Corrections. 
 
 Mr. Hickenlooper’s voice cracked as he spoke about Mr. Clements’s death. He called the shooting “an act of intimidation” that had cut down a thoughtful and deliberative man who had tried to reform Colorado’s prisons by reducing the number of inmates in solitary confinement. 
 
 “He did his job quietly and intently,” Mr. Hickenlooper said, joined by his cabinet and elected officials. “We are all grieving.” During his two years as head of Colorado’s prison system, Mr. Clements won praise from nearly everyone he met, from the governor to corrections officers, defense lawyers to former gang members. 
 
 The Rev. Leon Kelly, an antigang advocate who works to keep parolees from returning to prison, said Mr. Clements had embraced programs intended to prevent recidivism. Mr. Clements charmed Mr. Kelly’s 84-year-old mother so much that she put a photograph of him and her son on her dresser. 
 
 “He knew the job that needed to be done,” Mr. Kelly said. “He just jumped in with both feet hitting the ground.” 
 
 Mr. Clements held town-hall-style meetings with prison staffs. He tried to address the grievances of working long hours in a sometimes dangerous job. After he was seriously hurt in a bicycle accident, he climbed into a wheelchair last September to attend the funeral of a corrections officer who had been stabbed by an inmate. 
 
 Appointed by Mr. Hickenlooper in January 2011, Mr. Clements walked into a department facing budget cuts and a dwindling number of prisoners. He oversaw the closing of two prisons, a difficult process that can reverberate across communities that depend on the associated jobs and state money. 
 
 Mr. Hickenlooper said Mr. Clements had been supportive of the gun measures but was not “particularly active” during their emotional and contentious path toward passage. 
 
 The new laws require background checks for private gun sales in addition to the checks already mandated for purchases at shops and gun shows. They also ban ammunition magazines with more than 15 rounds, a feature that the governor said could turn “killers into killing machines.” 
 
 “If they’re slowed even for just a number of seconds, that allows someone to escape,” Mr. Hickenlooper said. 
 
 As he signed the bills, he was joined in his office by a handful of people who lost loved ones in shootings at Columbine High School in 1999, at an Aurora movie theater in July and at Sandy Hook Elementary School in Newtown, Conn., in December. 
 
 “I started crying,” said Tom Mauser, who became a gun control advocate after his son Daniel was killed at Columbine. 
 
 Mr. Mauser wore a suit to the Capitol on Wednesday in a nod to the formality of the occasion. But on his feet were Daniel’s sneakers. ||||| MONUMENT — The head of Colorado prisons was shot to death as he answered the front door of his Monument home, triggering a massive murder investigation and prompting extraordinary safety precautions around the state in case the killer targets other government officials. 
 
 Tom Clements, 58, executive director of the Colorado Department of Corrections, died Tuesday night at his home on the 17400 block of Colonial Park Drive. 
 
 His wife, Lisa, told a 911 dispatcher that someone rang the doorbell and then shot her husband in the chest, according to a dispatcher's recording that described her as "very distraught." The call came in at 8:42 p.m. 
 
 Within minutes, deputies found Clements and his wife inside the home on a set of stairs. Medical crews started performing CPR on Clements while deputies worked to secure the area and search for a suspect. 
 
 Clements is survived by his wife and two adult daughters, Rachel and Sara. 
 
 "Our family has lost a devoted husband and a beloved father," Clements' family wrote in a media release. "There are no words at this time to describe our grief and loss. We thank our friends and those praying for us here and across the nation. Your well-wishes and prayers bring us strength." 
 
 Scores of sheriff's deputies and investigators from state, local and federal agencies investigated through Wednesday at Clements' home in an upscale, wooded neighborhood east of Interstate 25. The two-story home was cordoned off, and deputies used dogs to search the area. 
 
 "We have no known suspect at this time," said Lt. Jeff Kramer, spokesman for the El Paso County Sheriff's office. 
 
 It does not appear that robbery was a motive for the shooting, Kramer said. Despite Clements' prominent position, authorities have not ruled out the possibility of a random shooting, he added. 
 
 "There is no evidence of a home invasion," he said. 
 
 Gov. John Hickenlooper and others praised Clements for innovations that helped decrease Colorado's recidivism rate and dramatically reduced the number of inmates in segregation. 
 
 Investigators comb the area surrounding the home of state prisons chief Tom Clements east of Monument. (Steve Nehf, The Denver Post) 
 
 But not all of Clements' changes have been popular among the rank-and-file. Two prisons closed under Clements' watch, and he would soon have been involved in deciding which other prisons to close in response to a dwindling prison population. 
 
 "We know of his position and realize that it is a possible motive for a crime such as this," Kramer said. 
 
 So far, the biggest clue linked to the killer is a car. 
 
 Authorities are looking for a "boxy," two-door, late-model car that a neighbor spotted outside Clements' home around the time of the shooting, Kramer said. 
 
 The witness said the car was running with no one in it Tuesday night. There are no street lights in the area. 
 
 Minutes later, the car was gone. 
 
 The car may be a dark-colored Lincoln or a Cadillac. A witness reported seeing a light green glow coming from the dashboard. The car was last seen Tuesday night traveling west on Higby Road before turning south onto Jackson Creek Parkway. Anyone who may have seen a car matching this description is asked to call authorities at 719-390-5555. 
 
 Investigators also want to speak with a woman seen speed-walking near Clements' home not long before the shooting. The woman was wearing light pants, a dark windbreaker and possibly a hat. The woman is sought because she may have seen the suspect, Kramer said. 
 
 When asked whether Clements had received death threats, Alison Morgan, DOC assistant director of finance and administration, declined to comment other than to say, "Corrections is inherently a dangerous business." 
 
 Lisa Clements reported that her husband Tom was shot and killed by someone who rang the bell at their secluded Monument home. (Helen H. Richardson, The Denver Post) 
 
 Morgan also wouldn't say whether DOC provided Clements with personal security, including surveillance at his home and staff security outside his office. 
 
 She said all of Colorado's prisons have been placed in modified lock-down as a result of the slaying. Inmate educational and work programming has been canceled temporarily for security reasons, she said. Visitation is curtailed until further notice. 
 
 Capt. Jeff Goodwin, spokesman for the Colorado Bureau of Investigation, said patrol officers increased staffing significantly Wednesday at the state Capitol, the governor's mansion and the governor's security detail. 
 
 "We have a responsibility to protect the governor and his family," Goodwin said. "Other people at the Capitol benefit from that increased security, as well." 
 
 The added security will continue for some time. 
 
 Sgt. Joe Roybal, spokesman for the El Paso County Sheriff's Department, said investigators are following numerous leads, but so far none has led to a specific suspect. 
 
 "If we feel we're close to identifying a suspect, we don't publicize that because we don't want to scare a suspect off," Roybal said. 
 
 Clements' death occurred a week after he denied a request by a Saudi national, Homaidan al-Turki, to serve out the remainder of a Colorado prison sentence in Saudi Arabia. He cited al-Turki's refusal to undergo sex-offender treatment in his denial, The Associated Press reported. 
 
 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. Prosecutors said al-Turki kept a housekeeper a virtual slave for four years in his home and sexually assaulted her. A judge reduced the sentence to eight years to life. Al-Turki insisted the case was politically motivated. 
 
 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. 
 
 Dave Joly, Denver spokesman for the FBI, said agents are looking at all angles. He did not say if federal agents joined the investigation as a result of the al-Turki case. 
 
 "Nothing is off the table," Joly said in an e-mail. "If a lead comes up in another state or out of the area, the FBI is here to assist in any way we can." 
 
 Mike Knight, chief investigator for the Arapahoe County District Attorney's office, said the prosecutors who worked on the al-Turki case and other high-profile investigations are taking increased security measures as a result of the slaying. 
 
 Knight would not specify what those measures are, but he said they were initiated by the DA's office and not on advice of law enforcement. 
 
 "Out of an abundance of caution for the attorneys who worked on those cases, we wanted to make sure that they take precautions," Knight said. 
 
 Roybal declined to say whether investigators are looking at the al-Turki connection. 
 
 Clements' home, like others in the Bent Tree Subdivision, is nestled in woods, well off Colonial Park Drive. 
 
 Several neighbors told The Post they knew Clements lived in the subdivision, but they didn't know the couple well. They said they didn't see or hear anything unusual Tuesday night. 
 
 Hickenlooper appointed Clements in January 2011. He came to Colorado from Missouri. In Colorado he supervised a staff of 6,022 employees at 20 public prisons. There were 20,379 Colorado inmates as of the end of 2012. 
 
 Tony Carochi, appointed Wednesday as DOC interim executive director, wrote to all corrections employees. 
 
 "Even as the hours have passed since we first learned about the death of Mr. Clements, the shock and grief still feels unreal," Carochi wrote. 
 
 "Obviously, the department is supporting (the investigation) any way we can," Morgan said. "We won't do anything to interfere and we will not speculate on any specific motive." 
 
 Hickenlooper ordered all flags lowered to half-staff until the day after Clements' funeral. In the afternoon, Hickenlooper met with DOC employees. 
 
 Kirk Mitchell: 303-954-1206, kmitchell@denverpost.com or twitter.com/kmitchelldp 
 
 Kieran Nicholson, Tom McGhee, Joey Bunch, Christopher Osher and Jeremy Meyer contributed to this report.
– Tom Clements, the executive director of Colorado’s department of corrections, was shot dead last night—but the who and why remain a mystery. Clements was shot fatally in the chest as he answered the door of his home in Monument, Colo., reports NBC, but nobody else in the house was harmed. Although there's no clear connection, the timing is notable: the shooting comes on the eve of tough and controversial new gun laws in the state, following the movie theater massacre in Aurora last year. Colorado Gov. John Hickenlooper is expected to sign new legislation today that will restrict magazine capacity and expand background checks on private and online firearms sales. But his first duty this morning was instead to pen a letter to Department of Corrections employees. "I can hardly believe it, let alone write words to describe it," wrote Hickenlooper. "I am so sad. I have never worked with a better person than Tom, and I can't imagine our team without him."