Murphy is from Plymouth, Michigan and was visiting Hawaii at the time of his disappearance. On the day he vanished, he planned to climb Mauna Kea although a state ranger warned him the terrain was rough and bad weather was expected. Murphy left his car, with his wallet inside, at the Onizuka Center visitor information station at the 9,000-foot level at noon. He told a visitor center employee that he planned to hike Humuula Trail, a steep path to the summit of the 13,796-foot mountain. That night there was a blizzard at the summit of Mauna Kea, with deep snowdrifts and winds up to 70 miles per hour, and temperatures dropped below zero.

Murphy has never been heard from again and an extensive search turned up no sign of him. He is presumed to have perished on the mountain, perhaps in a fall.