BARRON - Officials are looking into a letter purported to be from Jake Patterson, the man prosecutors say kidnapped 13-year-old Jayme Closs and murdered her parents.

The internet tabloid Radar Online claimed on Monday to have obtained a copy of a letter in which Patterson appeared to reply to someone who had written him. Patterson is being held at the Polk County Jail on a $5 million cash bond as he awaits arraignment on March 27.

The 21-year-old, who is charged with kidnapping Jayme and fatally shooting her parents, James and Denise Closs, was bound for trial earlier this month.

In the letter, Patterson thanked the person for writing him and said his family still supports him, even though he doesn't "deserve it." He noted that he went from never committing a crime to "doing the worst thing a human can do."

"Just one big f*** up haha," he wrote.

Patterson also mentioned Jayme in the letter, decorating her name with hearts. He said the two of them cooked together. At the bottom of the page is a drawing of a cross.

Barron County Sheriff Chris Fitzgerald said the letter "appears" to be from Patterson, but he couldn't say with certainty when contacted by a reporter Tuesday. He said investigators are working to ensure the letter didn't violate Patterson's bond, which prohibits him from contacting Jayme or the Douglas County residents who helped her following her escape last month.

As long as it's not a bond violation, Patterson has the legal right to write whoever he wants, Fitzgerald said.

“He can send you a letter all day long," he said. "Nothing I can do about it.”

Fitzgerald said investigators believe the letter was mailed to an out-of-state address. Polk County Sheriff Brent Waak declined to comment.