Joseph Halpern disappeared while hiking near Taylor Peak in Rocky Mountain National Park on August 15, 1933. He had gone camping in the area with a friend but decided to venture up Taylor Peak alone carrying an Army knapsack. Unfortunately, he never returned, and his friend alerted authorities when he failed to show up.

A snowstorm hit the region in the following days, making it more difficult to find Halpern. Despite an extensive search of the mountains, no sign of him was discovered. Following his disappearance, there were unconfirmed sightings of him across the country, including Phoenix, Arizona in December 1933, and traveling with the Lewis Brothers Circus in Detroit, Michigan, during the summer of 1935. However, none of these reports could be substantiated.

Halpern was a graduate student at the University of Chicago and had a summer job at an observatory in Wisconsin. He was talented in mathematics, chemistry, astronomy, and chess. Despite the passage of time, authorities have taken DNA from his relatives to identify his body if it is ever located, though they are no longer actively investigating the case.