MEXICO CITY -- Prosecutors have launched an investigation of possible criminal conduct in the case of a 14-year-old girl mistakenly sent to the U.S. to live with a woman who claimed to be her mother, authorities said Friday.

Alondra Luna Nunez was returned to her family in Mexico on Wednesday after DNA testing in the United States showed she was not the long-missing daughter of Houston resident Dorotea Garcia.

The Prosecutor's Office in the southwestern state of Michoacan said in a statement that it is looking into the case involving a civil court judge in Los Reyes, including media reports and videos that "suggest probable acts against the child's best interests and could constitute an illegal action."

Video footage of Alondra being taken screaming by police circulated widely and attracted national and international attention to the case.

Alondra had asked for DNA tests in Mexico before she was sent to the United States, and her parents presented more than a dozen documents including her baptismal records, family photographs and a copy of her birth certificate.

But Judge Cinthia Elodia Mercado ruled Alondra was in fact Alondra Diaz Garcia, who was taken from Texas by her father in 2007. The other girl remains missing and the father's whereabouts are also unknown.

Elodia Mercado said this week that it was not within her authority to order DNA testing, and she was obligated to ensure Mexico followed international conventions on child abductions.

"We, as judges, are only responsible to resolve the case with respect to recovering the minor," she said. "We don't do investigations or make inquiries."

Mexico's National Human Rights Commission also announced it had requested reports from a half dozen government entities to conduct its own inquiry into whether Alondra's human rights were violated.

It added that its officers had interviewed Alondra's father and offered medical and psychological help for the girl and the family, and said it would study whether procedures for handling such cases should be reformed.

"If there are holes or gaps in the protocol, these must be corrected to prevent future human rights violations that harm girls, boys and adolescents," the commission said in a statement.

After the ruling, Alondra travelled by bus with Garcia to the U.S. border, crossing at Laredo, Texas. Alondra was granted entry based on the birth certificate of Garcia's daughter and the court order, according to Mexico's Foreign Ministry.

This week, when asked if she harboured any anger about the forced weeklong separation from her family, Alondra, singled out the judge.

"I'm angry only at her, because it was her who caused all this," Alondra told The Associated Press. "Nobody but her is guilty. At least that's what I think."