Sabrina Allen: Moment Missing Girl's Father Found Out She Was Safe Sabrina Allen was 4 when she disappeared following a visit with her mother.

 -- After 12 years of clinging to hope that his missing daughter would be found safe, a Texas father is now waiting to reunite with the little girl who was taken from him.

Sabrina Allen, who was 4 when she went missing, was located in a small town southeast of Mexico City on Tuesday, authorities said.

Now 17, Allen was taken into custody, along with her non-custodial mother, Dara Llorens, and was flown back to Houston late Tuesday, authorities said.

"I'm going to ask her if I can give her a hug," the girl's father, Greg Allen, said through tears at an emotional news conference today. "She's in pretty bad shape as far as my understanding ... She was not living a regular life. She has not been going to school."

On April 19, 2002, Llorens allegedly took her daughter for a scheduled weekend visit as part of a court-ordered child custody agreement.

According to the FBI, Llorens never returned Sabrina to her father, who was her primary guardian, at the end of that weekend.

Acting on a tip from a confidential informant, Mexican officials worked with a team from private investigator Philip Klein's office to locate Allen and Llorens on Tuesday morning at a small apartment in Tlaxcala, authorities said.

Llorens was booked into Travis County Jail on an aggravated kidnapping charge. It was not immediately known if she had hired an attorney.

As Sabrina Allen readjusts to life in the United States, her father said he hopes she has some memories of their time together from before she was taken.

"I want to know her. She’s a completely different person, but they say personalities are formed by age five," Allen told ABC News' Austin affiliate KVUE in an exclusive interview. "[I'm] hoping she has some memories still.”

Allen said hiring Philip Klein as a private investigator and setting up a website for tips allowed him to never give up hope that he would one day be reunited with his daughter.

"Phil told me finding her would be the easy part. Getting her out will be the hard part," Allen said.

Now that Sabrina Allen is back home, Allen said he's patiently waiting to reunite with the daughter he worked to bring home for 12 years.

"She needs time to relax and just be a kid," he said.

ABC News' Dina Abou Salem contributed reporting.