Before dawn, a woman with her 18-year-old son in her car flagged down a sergeant at Riverside's Magnolia Avenue police station with a startling request.
She said she wanted to turn in her son, who had earlier called her to say he had molested two boys, 8 and 4, in a motel room.
After interviewing her son, Joseph Hayden Boston, Riverside police jailed him at the Robert Presley Detention Center on Saturday with bail set at $1 million.
In a statement, Riverside police said Boston confessed to sexually assaulting up to 50 children in other cities, starting when he was 10 years old.
Before moving to Riverside in early November, Boston had lived in Lakewood and Buena Park.
In Riverside he was staying at the Simply Home Inn & Suites in the 9800 block of Magnolia Avenue.
There, according to the police statement, he befriended the two boys who were staying at the motel with their parents. The boys were allowed to go into Boston's room Friday night. Hours later, police said, Boston called his mother, whose name was not disclosed, to tell her that he had molested the boys.
She then drove to the motel and took him to the police station.
Riverside County Child Protective Services responded and took custody of both children.
Lt. Joe Badali of the Los Angeles County sheriff's Lakewood station said the Sheriff's Special Victims Bureau was coordinating with Riverside detectives to determine if there is a "nexus with any victims out here."
There are no reported cases with ties to the Boston case, Badali said.
A spokesman for the Buena Park Police Department said the agency is aware of the investigation and will coordinate with Riverside but does not have any active cases involving Boston.
Riverside County district attorney's spokesman John Hall said the office had not made a decision Monday whether to file charges. Boston would likely be arraigned Wednesday if charges are filed.
Riverside Det. Paul Miranda asked anyone with information about other potential victims to call him at (951) 353-7945 or email at email@example.com.
Maximum penalties for sexual assaults, which depend on both the age of the perpetrator and the victim, have been stiffened in recent years and can be severe, said Paul Wallin, senior partner of Wallin & Klarich, a firm that specializes in sex crime defense.
Because Boston, who turned 18 in September, was an adult when the alleged crimes were committed and because the two victims were under 10, the maximum penalty would be 15 years to life in prison for each offense, Wallin said.
According to the firm's website, which cites research by the U.S. Department of Justice Office of Juvenile Justice and Delinquency Prevention, juveniles account for more than a third of those known to law enforcement to have committed sex offenses against other minors.
2:30 p.m.: This article was updated with comments from Wallin.
10:20 a.m.: This article was updated a statements from the Los Angeles County Sheriff's Department and Riverside County district attorney's office.