Matthew Taylor Coleman, a California surfing school owner, was charged on Wednesday with killing his two young children with a spear gun in Mexico, authorities said. The US attorney‘s office said in a statement that the 40-year-old, a resident of Santa Barbara, is facing a federal charge of the foreign murder of US nationals, Associated Press reported.

According to an affidavit filed by a Federal Bureau of Investigation (FBI) agent, Coleman confessed to the killing of his children – a 2-year-old son and a 10-month-old daughter. He took them to Rosarito, Mexico and shot them in their chests with a “spearfishing gun.”

In an interview with the FBI, Coleman said that “he believed his children were going to grow into monsters so he had to kill them,” AP reported, quoting a court document.

Coleman, during an interview with an FBI agent, said that “he was enlightened by QAnon and Illuminati conspiracy theories and was receiving visions and signs revealing that his wife, A.C., possessed serpent DNA and had passed it on to his children,” according to the affidavit.

Because of this, he believed that “his children were going to grow into monsters so he had to kill them.”

Authorities said that a farmworker found the children’s bodies at a ranch near Rosarito in Baja California.

According to Mexican authorities, Coleman and the children had checked into a Rosarito hotel on Saturday last week, but video footage showed them leaving before dawn on Monday.

The man returned alone later that morning and then left the hotel for good, authorities said.

When questioned, Coleman’s wife said to the Santa Barbara police that her husband had left with the children in the family’s van. But she didn’t know where they were going, and he hadn’t answered her text messages.

She further added that she didn’t believe the children were in any danger, that she hadn’t had any problems with Coleman, and “they did not have any sort of argument” before he left, according to the court affidavit.

An iPhone-finding application placed Coleman’s phone in Rosarito on Sunday, and on Monday it was traced to an area of Mexico near the San Ysidro Port of Entry in San Diego, according to the affidavit.