Update: 16-year-old arrested on suspicion of murder in case of missing Menifee boy

Investigators dig behind a Menifee property in the search for a missing 11-year-old autistic boy on Wednesday July 10, 2013.
Investigators dig behind a Menifee property in the search for a missing 11-year-old autistic boy on Wednesday July 10, 2013.
Investigators dig behind a Menifee property in the search for a missing 11-year-old autistic boy on Wednesday July 10, 2013.
Terry Dewayne Smith
Via NBC L.A.

UPDATE 4:37 p.m.: 16-year-old arrested; authorities try to ID human remains

A 16-year-old family member has been arrested in the presumed death of Terry Smith, the autistic boy who was reported missing in Menifee on Sunday, NBC L.A. reports.

Menifee Police Chief John Hill made the announcement at a press conference on Wednesday afternoon but would not identify the family member or any other information about the suspect.

The boy's house had earlier been cordoned off as a crime scene as police searched for and found human remains, though it was still unclear whether the remains belonged to 11-year-old Smith.

EARLIER: The search for an 11-year-old autistic boy took a disturbing turn on Wednesday as authorities began treating his California home as a crime scene and searched for human remains.

Terry Dewayne Smith Jr. was reported missing on Sunday in the Riverside County community of Menifee. Searches of the area with a bloodhound and a helicopter were unsuccessful.

Hundreds of volunteers later joined the effort in scorching heat but also failed to find the boy.

Menifee Mayor Scott Mann said in an email that investigators were trying to determine if there were human remains on the property.

TV news helicopters showed investigators gathered around a hole in a fenced area several dozen feet from the home in a semirural area 70 miles southeast of Los Angeles, where temperatures have topped 100 degrees.

NBC Los Angeles reports aerial footage showed investigators unearth what appeared to be a body. According to the site:

Aerial video showed investigators with a rake, shovel and other hand tools behind a property blocked off by the crime scene tape. The dig area was along a fenceline next to a large tree behind the Smith residence.

Authorities placed what appeared to be a body on a gurney.

Sheriff's detectives were led to the home shortly after 1 a.m. Wednesday by evidence indicating there might be a body on the property, Deputy Albert Martinez told the Riverside Press-Enterprise.

Further details were not released, but the search was suspended by the Riverside County Sheriff's Department.

"Our searchers are on standby. We are waiting to see what investigators find on the property," Martinez told KNX-AM radio.

Volunteers, however, planned to keep searching the surrounding area for the boy.

"Until we have absolute confirmation from the sheriff directly, we will continue to do our job, which is to search," said a posting on a Facebook page where the volunteer search was organized.

About 1,000 people, including deputies on horseback, emergency workers and volunteers, joined the effort on Tuesday.

Authorities were concerned that Terry wandered away without food, water or his medication.

The 4-foot-8 boy with sandy brown hair and brown eyes was last seen wearing blue basketball shorts. Local children were asked to not wear blue to avoid confusion.

Terry was last seen Saturday night, reportedly following his 16-year-old half-brother, who told the boy to go home, the Desert Sun said. The boy's mother said she didn't realize he was missing until the next day.

She shared details of the boy's habits on the searchers' Facebook page. Without his medication, Terry may be "over sensitive and may be walking on his tiptoes," the page said.

Searchers were also instructed to use his nickname "Juju" because hearing his full name called out might cause him to think he's in trouble and flee.