Mellenthin, a German immigrant, faced significant discrimination during the First World War, but he ironically died while trying to arrest an army deserter. Two San Juan County deputies and Mellenthin, who was 34 at the time, located the suspect at a sheep camp on Pine Bluff, a few miles north of the Town of La Sal in the national forest, according to information from the U.S. Department of Agriculture.
When Mellenthin informed the suspect of his arrest, he and his companion opened fire on the posse. Mellenthin was struck three times and was mortally wounded, but he managed to return fire and injure the suspect. The two surviving posse members returned to La Sal for help and later arrested the suspect and his companion. The army deserter was sentenced to life, but only served six years before receiving parole. The second suspect had his conviction overturned.
Ranger Mellenthin served nine years with the U.S. Forest Service. He was survived by his wife and children, and is buried in the Grand Valley Cemetery in Moab. The second-highest peak in the La Sal Mountains, at an elevation of 12,645 feet, is named in his honor.