A genealogy database used to match a family's DNA with evidence found at a 1973 crime scene has led investigators to identify the long-dead suspect in the strangulation killing of a young married couple, a Montana sheriff said Monday. Linda and Clifford Bernhardt, both 24, were killed at their Billings-area home in a case that would stymie investigators for decades. Investigators now believe they were killed by Cecil Stan Caldwell, a longtime city of Billings employee who was once a co-worker of Linda Bernhardt, Yellowstone County Sheriff Mike Linder said. He did not identify a motive in the killing.