By Bary Alyssa Johnson (staff@latinospost.com) | First Posted: Jul 11, 2013 02:11 PM EDT

A 16-year-old relative of a young, autistic boy was arrested on suspicion of murder on Wednesday after human remains were found in a makeshift grave on the family's Menifee, Calif. property.

According to a report from KLTA-5 News, police received a tip early on Wednesday morning regarding the possibility that a body had been found in the 38000 block of Helen Lane in Menifee.

"Officers on arrival located a partial grave containing partially exposed human remains," said Riverside County Sheriff's Capt. John Hill.

Police then confirmed on Wednesday that the body discovered in the shallow grave fit the description of missing 11-year-old Terry Smith, but the boy's identification is not yet conclusive.

At a news conference, Hill said that Smith's death was the result of a "domestic issue" in the house Terry lived in with his mother, Shawna Smith, a 13-year-old girl, and a 16-year-old half-brother, according to reports.

Guardian Express reports that after the body was found, authorities interviewed Shawna Smith, her partner and a 16-year-old stepbrother. After the interviews concluded, the Sheriff's Office said that "a 16-year-old brother" was arrested, but refused to elaborate on his relationship to Terry. A spokeswoman for the Sheriff's Office said that the teen's name will be released after formal charges have been filed.

The 16-year-old half-brother was reportedly the last person to see Terry before he disappeared, when he was put in charge of babysitting him on Saturday night. He told police that he was walking to the corner market when he noticed Terry following him and told him to go home. He says he never saw Terry again.

According to the manager of the corner market, the 16-year-old never came into the store on Saturday night.

"He wasn't at the market ... We had checked our surveillance, our cameras, all the video ... nothing," said a woman who worked at the store.

Terry was first discovered missing on Sunday morning at around 10:30 a.m., when his mother went to give him his medicine and discovered that his bed was empty. The police were called and hundreds of neighbors in the community began an all-out search for the boy, which spread over a 50-mile radius.

Fox News reports that investigators served a search warrant at Terry's house, hours after they told volunteers to call off their search efforts.

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