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A 12-year-old boy was tortured and beaten to death by his grandparents and a teenage uncle at their home in Montana, authorities said. In multiple instances, the suspects recorded themselves torturing the boy on their cellphones, police said.

James Hurley. Gallatin County Sheriff's Office

James Alex Hurley had been living with his grandparents, James Sasser Jr., 47, and Patricia Batts, 48, for about two years after the death of his father, who Batts identified as her biological son, according to a probable cause affidavit. His 14-year-old uncle, who is charged as a minor, also lived in the home. NBC News is not publishing the uncle's name because he is a juvenile.

The boy's mother lives in Texas. She said that she made numerous attempts to contact her son by phone at the grandparents’ home "but those attempts were systematically blocked by Batts," according to the complaint.

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All three suspects were arrested Wednesday and have been charged with one count of deliberate homicide.

James was found dead at the home near West Yellowstone on Feb. 3, the Gallatin County Sheriff's Office said.

A sheriff's deputy who responded to a report of his death that day "observed that the circumstances surrounding the death appeared to be suspicious," the affidavit states. The deputy said James had multiple wounds and contusions all over his body, prompting him to contact homicide detectives, according to the affidavit.

During the investigation into the boy's death, police seized cellphones belonging to the suspects that showed the family torturing him, the affidavit says.

The state medical examiner determined the boy died from blunt force trauma to the head, according to a probable cause affidavit.

In some of the videos from about two years ago, James "appeared to be a healthy and well-fed boy," the affidavit says, but he "appeared to be emaciated" at the time of his death. Investigators "observed that a good portion of the food in the house was locked away" and that Hurley would not have access to it, the affidavit says.

The family described James as recently becoming suicidal, erratic and hearing voices, according to the affidavit.

Despite these claims, detectives said they have not been able to find any record of the family reporting these alleged behaviors to law enforcement or attempting to get medical or psychiatric help.

The suspects appeared in court last week.

Bail was set at $500,000 for Sasser and $750,000 for Batts. They are both being held at the Gallatin County Detention Center. Their attorney did not immediately return a request for comment Tuesday. The uncle is being held at the Yellowstone Youth Services Center on $500,000 bail.