Anna Somoza (AZ Family).

A 4-year-old girl in Arizona was allegedly kept locked inside a "small dog crate" and "always bald" until she was eventually "left to die inside a sealed cardboard box," authorities and court documents say. Her mom is set to face charges after more than a decade on the run, according to federal officials.

Anna Somoza, 60, was arrested in Mexico on Sunday after a yearslong investigation into the 1997 death of her daughter, Crystal Reyes, who was "suffocated with a taped towel," according to the U.S. Marshals Service.

Somoza and her boyfriend, Avelino Tamala, were indicted by a grand jury in December 2014 on charges of first-degree murder. Tamala was arrested and convicted in 2016, but it would take investigators another 12 years to locate and apprehend Somoza, an effort "affected by her close connections with cartels," USMS officials say.

"This disturbing case can finally move forward with justice for Crystal," said U.S. Marshal Van Bayless for the District of Arizona in a statement. "Phoenix Police Department and Maricopa County Attorney's Office showed their unrelenting desire to get Somoza into court and prison for her atrocities to an innocent beautiful little girl."

Somoza, who is expected to be returned to the United States to face the charge, gave birth to Crystal on Nov. 25, 1993, in Nogales, Mexico, but the birth was never documented, according to investigators.

Shortly after Crystal was born, Somoza took the child to live with her and Tamala in Ahwatukee, Arizona. Tamala, a former Maricopa County sheriff's deputy, was not Crystal's biological father, according to federal officials.

"Behind closed doors, the young child was subjected to severe physical abuse, ultimately being confined to a small dog kennel," USMS officials said in a press release Sunday. "Throughout Crystal's brutally-short-lived life, Somoza and Tamala repeatedly tortured, starved, and abused Crystal as an infant and young girl. Reports indicate that Somoza and Tamala would leave Crystal bound by her hands and feet, gagged in a small dog crate for weeks at a time."

The abuse ended in Crystal's death on Jan. 30, 1997, when the 4-year-old was "bound, suffocated with a taped towel and left to die" inside the cardboard box, according to USMS officials.

Court documents from a 2018 Arizona Court of Appeals decision, in which Somoza is identified as "Anna Reyes," describe how a live-in housekeeper told investigators about Crystal being "very, very, very thin" and "skin and bones." The housekeeper alleged that Crystal was so weak she did not have enough breath to keep crying and she "would just whine … in the kennel," according to the documents.

"She would just whine, and really slowly," the documents say. "While in the kennel, [Crystal] not fed, and when [the housekeeper] attempted to feed [Crystal], Reyes commanded her to stop. At some point, [Crystal] stopped defecating."

The child was confined in the kennel for two to three weeks, according to the housekeeper. She was allegedly kept only in her undergarments and was "always bald" after Somoza helped shave the girl's head, according to court documents. She was treated differently from the other children in the home and was not allowed to interact with them or share meals with the family, the court documents state.

Her remains went unidentified for years after a hunter discovered human bone fragments in the Arizona desert in 1998. Investigators eventually collected DNA from Somoza and Tamala after the pair were arrested on drug and weapons offenses in 1999. Forensic testing could not rule out Somoza as the child's maternal source, but detectives lacked a DNA sample from Crystal's biological father, leaving the case cold.

Somoza served an eight-year federal prison sentence and was released in 2008 before being deported to Mexico, according to the Marshals Service.

The case broke open in August 2014, when cold-case investigators located Crystal's biological father, Darren Stockwell, who was a law enforcement officer at the time of the child's conception. Investigators collected his DNA, and testing positively identified the remains as Crystal.

That breakthrough and other evidence allowed prosecutors to charge Somoza and Tamala with first-degree murder in December 2014.

Tamala was found guilty of Crystal's murder on Nov. 8, 2016, and sentenced to life in prison, authorities said.

Somoza, meanwhile, allegedly worked hard to evade law enforcement in Mexico.

In October 2022, investigators obtained a provisional arrest warrant authorizing her extradition to the United States. The Marshals Service designated the fugitive investigation a major case in 2026, providing additional manpower and resources. Beginning in September, task force members developed information that Somoza was evading detection in Cuernavaca, Mexico.

On Oct. 18, 2026, Somoza was detained in Xochitepec by Mexican federal and Interpol authorities, according to USMS officials. Law enforcement agencies are coordinating her return to Arizona.