Coleman, 40, is charged with two counts of foreign first-degree murder of United States nationals. If convicted, Coleman would beeligible for the death penalty, according to the U.S. Department of Justice.

“There are no words to describe the profound grief that envelops an entire community when a child is murdered,” Acting U.S. Attorney Randy Grossman wrote in a press release. “The Department of Justice is determined to achieve justice for these victims and their loved ones.”

Coleman is expected to make his first court appearance on the indictment on Thursday in United States District Court in Los Angeles, according to authorities. He will appear in United States District Court in San Diego, where the case will be prosecuted, at a date that has not yet been determined.

Matthew Taylor Coleman.Instagram

Mathew Taylor Coleman

Police say Coleman drove the children — 2-year-old Kaleo and 10-month-old Roxy — into Mexico. Two days later, authorities allege, he took the kids to a ranch, where 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.

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

Matthew Taylor Coleman/instagram

Matthew Taylor Coleman

The sudden violence has shocked and saddened those who knew him.

“Our entire community is in mourning,” a surfing friend told PEOPLE. “We mourn the loss of Kaleo and Roxy, we mourn for Roxy, and we mourn the loss of our friend who we thought we knew.”

Coleman is being held at a federal prison after his arrest, and PEOPLE learned earlier this month thathe is being held in protective custodyso that he doesn’t interact with other inmates.

“He is in his cell about 23 hours a day,” said a source with direct knowledge of his incarceration. “He only sees his public defender. And he can’t have many personal effects in his cell. He’s got nothing but a Bible.”

Coleman has not yet entered a plea. The public defender’s office has not returned PEOPLE’s calls for comment.

source: people.com