Ranger Mellenthin was killed in the line of duty on August 23, 1918, after tracking and confronting an army deserter with two San Juan County deputies at Pine Bluff in the La Sal National Forest. He joined the Forest Service on August 1, 1909 and was assigned to the Moab District on the La Sal National Forest where he served until his death at the age of 34. Before his time with the Forest Service, Ranger Mellenthin had served with the German army. He was survived by his wife and children and is buried in Grand Valley Cemetery, Moab, Utah. Ranger Mellenthin’s name is on the National Law Enforcement Officers Memorial in Washington DC.