UPDATED 05/05/11 10:00 p.m.

GARY, Ind. (CBS) — Police say additional charges are expected soon in the death of 13-year-old Christian Choate, whose body was found buried in a shallow grave, encased in concrete, near a mobile home park in Gary last night.

He has been missing for at least two years

His father, Riley Lowell Choate, has been charged with several crimes, including failing to report the boy’s death, but not murder, Lake County, Ind., authorities said.

As CBS 2’s Suzanne Le Mignot reports, an autopsy was performed Thursday morning and the death has been ruled a homicide, but the specific cause of death was not being released until the investigation is completed. DNA testing is also taking place.

Lake County, Ind., Sheriff’s police say an anonymous tip from an out-of-state caller tipped them off to the boy’s body, which was found Wednesday in the Colfax Mobile Home Park, in the 5900 block of West 36th Avenue.

“It was a very gruesome scene out there yesterday when the boy’s body was uncovered,” Sheriff John Buncich said.

The caller told police the boy had been missing under “mysterious circumstances,” and had been killed and buried.

LISTEN: Newsradio 780’s Bernie Tafoya reports

After the call Sunday that led police to the trailer park, Riley Lowell Choate was arrested and led police to the body, according to Bunchich.

“He advised he had buried the youth, wrapped him in a blanket and plastic and buried him in a shallow grave underneath the shed and put concrete on top of the body. He also indicated at the time, he put a Bible on the boy’s chest when he buried him,” Buncich said. “He also put lime on top of the body hoping to aid in the decomposition.”

County crime lab technicians worked for hours to break up about 2 feet of concrete to locate the body.

So far, Choate has been charged with removing a body from a death scene and failure to notify authorities of a dead body.

Choate told police he had an accomplice.

He had taken custody of Christian and his sister six years ago from their biological mother, who had given them up.

Police said Christian’s mother called 911 after speaking with a person in Kentucky, where Choate had moved. That person said Christian had never run away, as Choate had always maintained.

Instead, the teen had been murdered and buried at the mobile home park where his family once lived.

At the trailer park Thursday, neighbors said the boy’s family had moved to Kentucky two years ago. The family now living in the home where the boy’s family once lived said they did not want to be bothered, and wanted to be left alone.

Other neighbors said police were seen around the mobile home park all day Wednesday.

“I have kid; everybody in here has kids, and to think about something like that is unbelievable,” one woman said. “So many people in and out of that shed that the baby was under. He’s just 13 years old; still a baby.”

Buncich said additional details would be available after charges are filed. “We have some other people out of state we need to talk to,” he said.

Lake County Sheriff’s detectives left for Hopkinsville, Kentucky to question the teen’s relatives on Thursday.

The ex-boyfriend of Christian’s mother, Daniel Nieto, and his daughter, Alyssa, lived with the young man in his formative years and considered him a family member. Alyssa says she tried to contact Christian in recent years but was told, “No, you can’t see him.”

Daniel Nieto says Christian endured abuse at the hands of his parents.

The boy’s mom is in jail in Kentucky in an unrelated case.

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