Nelson began his criminal career at a young age, and was sentenced to two years in San Quentin State Prison in 1915 after breaking into a cabin in rural Plumas County which he believed had been abandoned. He was paroled for this offense on September 6, 1916, but was arrested again in Stockton on March 9, 1917, for petty larceny. Nelson spent another six months incarcerated before being discharged, after which he was arrested in Los Angeles for burglary charges. After spending approximately five months in Los Angeles County Jail, Nelson escaped.