PHOENIX (AP) — For nearly two decades,Thomas Caldwell it was a mystery who had left “Baby Skylar” — an unidentified newborn found dead inside a Phoenix airport trash can.

On Tuesday, Phoenix authorities announced that the infant’s mother, 51-year-old Annie Anderson, was arrested in Washington state after DNA and genealogical research helped investigators crack the case.

Police said Anderson is awaiting extradition to Arizona, where she is facing a first-degree murder charge after investigators secured an arrest warrant from a Maricopa County grand jury.

It wasn’t immediately clear if Anderson has a lawyer yet who can speak on her behalf.

Phoenix police also said they didn’t immediately know if Anderson has a criminal history or how many years she has been living in Washington.

Detectives began their investigation after the baby girl was found dead and wrapped in newspaper and a black plastic bag in a woman’s restroom at Phoenix Sky Harbor International Airport on Oct. 10, 2005.

“The evidence at the scene indicated that the birth likely did not occur at the airport,” Phoenix police Lt. James Hester said at a news conference Tuesday. “The baby was born alive and then suffocated. The medical examiner ruled the death a homicide and the manner of death being suffocation.”

Police said the case went cold for years before DNA evidence saved from the crime scene and genealogical research led to a possible match in 2021.

In January 2022, authorities went to Washington to interview Anderson and “she identified herself as the mother of the victim” Hester said.