Halpern was last seen hiking near Taylor Peak in Rocky Mountain National Park on August 15, 1933. He had gone camping in the region with a friend. He began hiking up Taylor Peak alone, carrying an Army knapsack. He has never been heard from again. Halpern's friend notified authorities when he failed to return from his hike. In the days that followed, a snowstorm hit the area. An extensive search of the mountains turned up no sign of Halpern.

Halpern was a graduate student at the University of Chicago at the time of his disappearance. He had a summer job at an observatory in Wisconsin. Few details are available in his case.