The FBI (search) announced late Friday that a missing New Mexico toddler who was the subject of a nationwide Amber Alert (search) has been found unhurt and turned over to state social workers.

Justin Black was in the custody of the state Children, Youth and Family Department (search), FBI Special Agent Andreas Stephens said. He provided no details about the boy's recovery.

Stephens credited the 16-month-old boy's quick return to New Mexico to the diligent efforts of FBI agents around the country as well as New Mexico State Police (search) and Mexican authorities.

Authorities were still looking for the child's stepfather, 22-year-old Ivan Villa. He and the child disappeared from the Ruidoso apartment where Justin's mother was found strangled Sunday, Mother's Day.

Villa is wanted on a felony kidnapping warrant. Police also want to talk with him about the death of Kristi Black, 19, but they have not called him a suspect.

On Wednesday, the National Center for Missing and Exploited Children (search) in Alexandria, Va., faxed some 10,000 fliers with photos of the toddler and Villa to businesses and agencies in areas where investigators believe the pair might have traveled. The boy's photo also appeared at the top of the group's Web site.

Authorities got a break in the case earlier this week when Black's car was found abandoned in a residential neighborhood in Ciudad Juarez, Mexico, across the border from El Paso, Texas. They also had a tip that a man fitting Villa's description was spotted carrying a baby across the Santa Fe International Bridge on the border with Mexico.

Authorities also chased leads in El Paso and Chicago, where Villa has family.

On Sunday, police responded to a call of a verbal dispute between Black and Villa at the couple's Ruidoso apartment. Police said they did not make an arrest because they saw no evidence of physical violence and the couple agreed to separate.

Several hours later, a friend went to the apartment and found the woman's body.

Black worked at the Ruidoso Downs horse track with Villa. Family and friends described her as a dedicated mother and hard worker.