Ontario Police say they received a 911 call from a pay phone, with the victim reporting she had been kidnapped and sexually assaulted by a man who claimed to be a police officer.
According to investigators, the woman was walking down the street, when Siefert pulled alongside and offered a ride. Also according to police, the victim got into the vehicle and exposed her breast after the suspect offered her money.
Investigators say the suspect identified himself as a police officer and told the woman she was under arrest and began fondling her.
She was eventually released near where she was picked up.
Ontario Police say Siefert is a registered sex offender. They say he has a prior arrest in Chula Vista in 1996 involving similar circumstances including rape and impersonating an officer.
Investigators are concerned there could be other victims. Anyone with information is asked to call Detective M. Guski at (909) 395-2726.