SAN DIEGO (CBSLA.com) — A Whittier couple has been arrested trying to enter Mexico with the body of a 2-year-old child in a duffel bag, police said Wednesday.

Johnny Lewis Hartley, 39, and Mercy Mary Becerra, 43, were arrested by Mexican authorities Tuesday after being denied entry into Mexico.

According to police, the pair tried to cross the border, but when they were stopped by Mexican Customs agents, Becerra fled and left Hartley with the duffel bag. An X-ray of the bag revealed a body inside, and further examination determined that it was a 2-year-old girl, police said.

Becerra was later taken into custody by Mexican authorities, and both were turned over the U.S. Customs and Border Protection.

San Diego police homicide detectives, after interviewing the couple, determined the incident that may have led to the child’s death may have occurred in Whittier, according to officials. Investigators do not believe the suspects are the child’s parents.

CBS2’s Amy Johnson said authorities did not say how the three were linked.

She spoke to former neighbors who were shocked the couple could be accused of such a horrific thing.

“I can’t believe that., it’s just really sad,” said Henry Munoz. “That someone could do that.”

He said the couple lived in apartment 3 with a number of children. Two twins, a couple of older ones. Four were in their teens.”

“There were a lot of kids there,” he said, “they had like eight kids.

Both Hartley and Becerra were both booked on one count of murder and child cruelty leading to death.

San Diego police Lt. Ray Valentin declined to say whether the girl’s body bore any signs of injuries.

San Diego and Whittier police detectives are working together on the case.