It was a crime that seemingly had no warning.

But she was wrong.

Police say Coleman, a 40-year-old surfing instructor, drove the children into Mexico. Two days later, authorities allege, he took the kids to a ranch, were he killed them with a spearfishing gun and returned to his hotel a few hours later. He was arrested when he attempted to cross the border back into the United States.

matthew taylor coleman

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Kaleo and Roxy Coleman.Matthew Taylor Coleman/instagram

Matthew Taylor Coleman

“M. Coleman stated that he believed his children were going to grow into monsters so he had to kill them,” Bannon wrote.

Coleman is now being held in protective custody in an undisclosed federal prison. He has not yet entered a plea, and the public defender’s office has not returned PEOPLE’s calls for comment.

While the case progresses, people close to him — including his wife — want to know what happened.

“She hopes to be able to ask him for answers face to face someday,” says the friend, “but for now, she’s just grieving. We all are. It’s an absolute nightmare.”

source: people.com