Conrad had worked at the hotel for seven years before she was killed Dec. 3, 1976, at age 38.
Investigators had not been able to identify a suspect from the evidence they collected during the initial investigation, but the Colorado Bureau of Investigation and the Colorado Springs Police Department Laboratory -- working with a grant from the National Institute of Justice -- identified Robert Baillie, 58, as a suspect, The (Colorado Springs) Gazette reported Thursday.
Baillie -- who is scheduled to be eligible for parole in January 2014 in the sexual assault case -- was arrested Wednesday at the Fremont Correctional Facility in Canon City, the newspaper said.
A co-worker initiated the search for Conrad after the housekeeper seemed to vanish while at work. Conrad's body was found in a linen closet and a subsequent autopsy determined she had been sexually assaulted, beaten and strangled.
NBC reportedly holds celebs hostage to Jimmy Fallon's show
Aaron Carter is still in love with Hilary Duff