A New Mexico man who pleaded not guilty to the alleged kidnap and murder of an 11-year-old Navajo girl is scheduled to appear in court Tuesday for a change-of-plea hearing, according to multiple media reports.

Tom Begaye Jr., a member of the Navajo Nation whose alleged crimes prompted efforts to expand the AMBER Alert system to tribal lands, is expected to reverse his plea when he appears in an Albuquerque federal court, according to KRQE, ABC News and the Associated Press.

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It was unknown whether a deal had been struck between his attorneys and prosecutors, reports the AP.

Begaye, 28, of Waterflow, was arrested on May 4, 2016, after Ashlynne Mike’s body was found a few miles south of the famed Shiprock monument in New Mexico, two days after she and her 9-year-old brother went missing near their Lower Fruitland home.

Police said the two children were at a bus stop after school when a stranger in a van allegedly offered to take them to a movie, and the reluctant boy agreed to go along because he did not want his older sister to go alone.

Hours later, the boy was found by a passerby along the highway near the Arizona state line after he said he escaped.

Image zoom Tom Begaye San Juan County, N.M. Detention Center/AP

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The boy told authorities the driver had taken the pair into the desert, then walked off with the girl while carrying a crowbar. According to court documents, Begaye allegedly confessed to authorities that he sexually assaulted Ashlynne and hit her in the head twice with the blunt instrument, reports ABC News.

Begaye allegedly said the girl was still moving when he left her, but her body later was found in the remote location.

A New Mexico AMBER Alert for Ashlynne was not issued until around 2 a.m. the next day. The girl’s father subsequently filed a lawsuit against the Navajo Nation, arguing that his daughter’s life might have been saved if the emergency notification system had been in place on the 27,000-square-mile reservation, which stretches from New Mexico into Arizona and Utah.

In April, U.S. Sen. John McCain of Arizona introduced federal legislation to include tribal lands in the AMBER Alert program that broadcasts information about abductions.

In a six-count indictment, a federal grand jury charged Begaye with murder, kidnapping and aggravated sexual abuse offenses.