While on probation for a drunk driving conviction in August 1991, Preston was arrested for sexually assaulting a 16-year-old Mexican boy, after picking him up at a gathering point for day laborers. The boy told authorities that Preston took him to his Malibu home, smoked cocaine, showed him pornographic pictures and tried to assault him before he escaped. Preston was also charged with assault with a deadly weapon involving a man he picked up to do work at his home, the day before his arrest in the case involving the boy. After submitting to a drug test, Preston tested positive for cocaine. He entered no-contest pleas to the cocaine and assault charges. The sex charges which included misdemeanor charges of child molestation and exhibiting pornographic material to a minor were dismissed. He was sentenced to nine months at a drug rehabilitation center and three months of house arrest.