Clint Dunn / AP File Thirteen-year-old Hailey Dunn (left) poses for a photo with her mother Billie Jean Dunn and her mother's boyfriend Shawn Adkins on Dec. 25, 2010, in Colorado City, Texas. Authorities in West Texas on Friday confirmed the remains found in a remote part of Scurry County in March are those of Hailey Dunn, who has been missing for more than two years.

SNYDER, Texas — Remains found in a remote West Texas location last month are those of a 13-year-old middle school cheerleader missing since December 2010, authorities announced Friday.

Hailey Darlene Dunn's remains were found near Lake J.B. Thomas in Scurry County on March 16, more than two years after her mother reported her missing.

The girl's disappearance and the cause of her death remain under investigation, Scurry County Sheriff Trey Wilson said at a news conference Friday. The Scurry County District Attorney's Office received written confirmation of the identity of the remains on Friday, he said.

Texas Rangers informed the girl's mother, Billie Jean Dunn, on Friday afternoon at her Austin home, said her attorney, John Young. Dunn will be driving to West Texas to arrange her daughter's funeral, he said.

The body was found about 20 miles northwest of the girl's hometown of Colorado City. The girl had been the subject of months of intensive searches in and around Colorado City and surrounding fields and landfills after her mother reported her missing on Dec. 28, 2010. More than 100 billboards featuring her picture and information about the case were set up along interstates in Texas and other states.

The mother's boyfriend, Shawn Adkins, has said he last saw Hailey a day before she was reported missing. He said the girl told him she was going to her father's home nearby and then on to spend the night at a friend's home. She did neither.

Authorities had named Adkins as a person of interest in the girl's disappearance, but he was never charged. At one point, authorities accused the girl's mother of lying about the whereabouts of Adkins, who was found at her home. Billie Dunn pleaded no contest in June 2011 to making a false report to law enforcement and received a suspended 90-day jail term with probation.

The mother and Adkins have denied involvement in Hailey's disappearance.

Hailey's paternal grandfather, Bill Dunn, died in 2011, six months after the girl went missing. His widow, Spicy Dunn of Ponca City, Okla., said her husband spent much of the last months of his life trying to learn what became of his granddaughter.

"He was very, very hurt, and was on the computer all the time looking and trying to find anything that had to do with Hailey," she said Friday. "Anything."

She said family members made a point not to change their phone numbers so that law enforcement officials could reach them in case of any developments, even years later.

"It is a relief to know that she's at peace," Spicy Dunn said. "She doesn't have any more suffering."

She later added, "I hope the family comes to a closure. I know it's very hard."