Reagan, his mother Virginia Uden and his older brother Richard Uden were last seen on September 12, 1980. They were leaving Virginia's mother's residence in Riverton, Wyoming at approximately 1:30 p.m. and driving the family's station wagon to meet Virginia's ex-husband, Gerald Uden. He was going to take Reagan and Richard bird hunting and the boys had a rifle in the car with them. They never arrived at their destination and have never been seen again.

The Udens' 1973 Ford station wagon, which Virginia had borrowed from her mother, was found abandoned and vandalized on October 4, 1980, nearly one month after she and her sons had disappeared. The station wagon was located in the vicinity of the 700 block of north Federal Court in Riverton, Wyoming, near Dickson Park Road and Trout Creek Canyon in the Wind River Canyon region of Fremont County. It appeared as if someone had tried to push it into the canyon, but it became lodged on some rocks 75 feet from the top and did not fall all the way down. Someone then tried to conceal it by covering it with pine branches. Large amounts of Virginia's blood were found all over the car's interior.

In 2008, the case received new attention when investigators searched Gerald's former residence. He sold the property in 1985 and it went through several owners after that. Authorities believe Virginia is deceased, but they are uncertain as to the fate of her sons. Their cases remain unsolved.