Update: Matthew Taylor Coleman confessed to killing his two young children whose bodies were found earlier this week in Rosarito, Mexico, a federal criminal complaint filed Wednesday shows.

SAN DIEGO – Authorities took a Santa Barbara man into custody at the San Ysidro Port of Entry Monday morning after his two young children were found dead in Mexico.

The Mexican state’s Attorney General’s Office said 40-year-old Matthew Coleman could be extradited to Mexico to face charges in the slaying of the children, a boy and a girl aged between 1-3 years old. Their bodies were found Monday by a field worker in some brush on a ranch near Rosarito in the Mexican state of Baja California. Officials believe the children were stabbed to death with a wooden stake.

In a statement, the FBI said it is working with Santa Barbara police following a report they’d received on “three missing persons; one adult male and his two children who are believed to have crossed the southern border into Mexico.”

“A joint investigation is underway among the Santa Barbara Police Department, the FBI in Los Angeles and San Diego, U.S. Customs and Border Protection and Mexican authorities,” the agency said. “Currently, the adult male, is in federal custody and the investigation is continuing.” 

Prior to the incident, Border Report reported that Coleman checked into a hotel with his children Saturday. He reportedly went to a ranch in Rosarito on Sunday, where the children were later found.

The boy was stabbed 17 times while the girl was stabbed 12 times, according to Border Report.

The worker who found the children told Border Report that he was shocked to see blood spatter when walking out of his home. He told investigators that his dogs led him to the two “small bodies.”

“To be honest, I teared up,” the worker, who wished not to be named, said. “And I immediately notified my manager to call the police to come investigate. I was scared and sad because these are tiny children who don’t know any better. Hopefully, they find whoever is responsible because this is a terrible thing.”

Coleman was taken into custody around 7 a.m. Monday while heading back into the United States. He was stopped at the border due to an alert released by officials searching for him.

According to authorities, Coleman went to Point Loma Nazarene University for his undergraduate degree and attended UC Santa Barbara for his master’s degree. He also is believed to have owned a surf school called Lovewater.

Check back for updates on this developing story.