Robert Anthony Camou, 27, was found inside the 2017 Toyota Prius before officers surrounded the vehicle, officials said.
The whereabouts of the victim in the Monday morning abduction, 31-year-old Amanda Kathleen Custer, remained unknown.
Camou had previously been identified as the alleged kidnapper in the case, which authorities believe originated with a domestic violence incident.
Monrovia police said investigators found indications that Custer had been assaulted and taken against her will in the back of gray Prius sedan, with California license plate No. 8AOR167, in the 600 block of Vaquero Road.
Authorities said Custer and Camou had been in a tumultuous dating relationship over the last two years, one marked by multiple allegations of domestic violence.
Anyone with information about the abduction is asked to call the Los Angeles County Sheriff’s Department Homicide Bureau at (323) 890-5500. Anonymous information can be provided to Crime Stoppers at (800) 222-TIPS.
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