Two Whittier residents are behind bars in San Diego County Wednesday after a young child was found dead in a duffel bag one of them was carrying when they crossed into Mexico.

SAN DIEGO (CBS8/CNS) - Two Whittier residents are behind bars in San Diego County Wednesday after a young child was found dead in a duffel bag one of them was carrying when they crossed into Mexico.

Mercy Mary Becerra, 43, and 38-year-old Johnny Lewis Hartley entered Tijuana in a pedestrian lane about noon Tuesday, according to San Diego police.

Becerra ran off as Mexican customs agents approached the pair, SDPD Lt. Ray Valentin said. Authorities chased her and took her companion into custody.

The dead child, a girl believed to be about 2 years old, was discovered during an X-ray examination of the bag Hartley had been carrying.

Becerra was arrested nearby a short time later, Valentin said. Mexican authorities turned the detainees over to San Diego police.

After being interrogated by homicide detectives, Becerra and Hartley were booked into county jail this morning on suspicion of murder and child cruelty leading to death.

Investigators do not believe the suspects are related to the child and are working with Whittier police to identify her and her parents, the lieutenant said.

Valentin declined to disclose whether the toddler's body bore signs of suspicious injuries. A cause-of-death ruling was on hold pending an autopsy.

Though the child is believed to have been killed in the southern Los Angeles County city, Becerra and Hartley are expected to be prosecuted in the San Diego area, according to Valentin.

The suspects were being held without bail pending arraignment, scheduled for Friday afternoon.