Matthew Taylor Coleman.Photo: Instagram

Mathew Taylor Coleman

Months after he was arrested for allegedlykilling his two childrenwith a spearfishing gun in Mexico,Matthew Taylor Colemanhas sent a handwritten letter from prison to at least one friend, asking for forgiveness.

“He’s really despondent and hopeless,” the longtime family friend tells PEOPLE. “He’s alone with his thoughts 24/7. He’s reflecting on the mistakes he made in life and wondering if there’s any chance for redemption.”

“He poured out his heart,” the friend says. “He begged for forgiveness, but says that he’s now where he deserves to be.”

Police say Coleman drove the children into Mexico. Two days later, authorities say he took the kids to a ranch, where he allegedlykilled them with a spearfishing gunand returned to his hotel a few hours later. He was arrested when he attempted to cross the border back into the United States.

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.

Want to keep up with the latest crime coverage? Sign up forPEOPLE’s free True Crime newsletterfor breaking crime news, ongoing trial coverage and details of intriguing unsolved cases.

The FBI seized Coleman’s computers and phones, and believe that he spent hours surfing and posting on conspiracy theory message boards and groups.

Coleman wasindicted on murder chargesin September. If convicted, he is eligible for the death penalty. Coleman is now being held in protective custody in a federal prison. He has pleaded not guilty to the charges, and the public defender’s office has not returned PEOPLE’s calls for comment.

His childhood friend tells PEOPLE that he’s unsure if Coleman sent letters to anyone else, but that he was dreading the holidays in jail.

“He said he’s sorry, that he never wanted to cause pain, and that he’s working through why he made the choices he made,” the friend says. “It was a very sad note.”

source: people.com