Partial remains were found Wednesday afternoon in a shallow backyard grave at the home of Terry Dewayne Smith Jr., a high-functioning autistic 11-year-old whose disappearance prompted a search by police and more than 700 volunteers, NBC-TV, Los Angeles, reported.
The occupants of the home had been interviewed by investigators, and "as a result of those interviews, a 16-year-old family member was arrested," the TV station quoted Menifee Police Chief John Hill as saying.
No further details were provided on the family member, but Riverside County Sheriff's Department officials said earlier Terry's mother, Shawna Smith, her partner and a 16-year-old stepbrother had been interviewed at the sheriff's station.
Terry was initially said to have been last seen Saturday night in his stepbrother's room, but Wednesday the older boy said Terry followed him to a store that day. The stepbrother ordered him to return home, and has been missing since, Deputy Alberto Martinez of the Riverside County Sheriff's Office said.
Detectives began investigating the home Wednesday for human remains, the fourth day of the search for the boy, the Los Angeles Times reported.