(CNN) - The investigation into the slaying of Colorado's prison chief has produced few clues.
Tom Clements was gunned down Tuesday night when he answered the door at his home in Monument, about 50 miles south of Denver.
"We are looking at all potential tips, leads, threats that Mr. Clements may have had from anybody in that prison system," El Paso County Undersheriff Paula Presley says on CNN's "Starting Point" on Thursday. "The investigation is wide open at this point."
Asked whether the 58-year-old's killing might have been a professional hit, Presley replied, "We don't have any specific information that would lead us to that."
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