Advanced DNA testing techniques identified the mother of a dead newborn who was found inside a backpack in a creek more than eight years ago, state police said Tuesday.

Sarah Sue Hawk, 25, was charged Friday with criminal homicide and concealing the death of a child after DNA evidence conclusively determined she was the mother, Fayette County District Attorney Nancy Vernon said. When presented with the test results, Hawk admitted she was the girl's mother, Vernon said.

"Truly, this is a tragedy for all involved, including this mother," Vernon said.

Hawk was being held at the Fayette County Prison. Authoriities did not know Tuesday whether Hawk had an attorney.

The investigation into the newborn's death was rekindled after Trooper James Pierce, who was assigned the case last year, decided to re-examine young women who lived in the area, about 45 miles south of Pittsburgh.

Pierce said he had always thought the mother was from the area since the creek is isolated and hard for an outsider to find.

Pierce went to Hawk's childhood home near the creek and took a DNA sample from her sister, who still lived there. The test concluded the sister could have been a relative of the baby. With that, Pierce sought DNA samples from Hawk and her other sisters.

It was the tests that identify mitochondrial DNA, which is passed from the mother to baby, that gave police a conclusive match, Pierce said.

The newborn's body was found wrapped in a flannel shirt and grocery bags in June 2000 by two men who were catching minnows in Cove Run Creek. DNA samples from women in the area and other evidence was taken at the time, but no suspects were identified.

Fayette County Coroner Phillip Reilly said he could not determine an exact cause of death.