Aloys Krost, a 62-year-old physics professor from Germany, disappeared on October 1, 2013, while hiking the Pinnacle Trail in Lake Arrowhead, California. He was visiting the U.S. for a conference and joined a group hike in the San Bernardino Mountains. Around 5:45 p.m. he became separated from his companions and was never seen again.

Krost was described as an experienced hiker and hunter, yet he had no hiking equipment with him when he vanished. Extensive search efforts, including rescue teams and search dogs, covered rugged terrain but turned up no trace. Investigators believe he likely became lost in the wilderness, but the absence of physical evidence has left the disappearance unresolved.

If anyone was on the Pinnacle Trail or in the Lake Arrowhead area on October 1, 2013, or has information about Krost’s movements that day, please come forward.