(CNN) The man accused of kidnapping 13-year-old Jayme Closs and killing her parents reportedly expressed his remorse and detailed his plans for trial in a letter from jail.

Nearly two months after his arrest, Jake Patterson sent a letter postmarked February 28 to a journalist for KARE-TV , the station reported Thursday. In the purported letter, the kidnapping suspect talked about his remorse for what he did and said he plans to plead guilty to murder and kidnapping charges during his court appearance later this month.

Jayme Closs' accused kidnapper Jake Patterson wrote me a letter from jail, saying he committed the crimes "mostly on impulse" and that he plans to plead guilty on March 27 so her family won't have to "worry about a trial." https://t.co/XpK3Q19JCC

Authorities say Patterson, 21, held Jayme captive for 88 days inside his cabin in the remote town of Gordon, Wisconsin. She escaped January 10 and asked for help from a woman walking her dog, who took her to a nearby home and called the police. Patterson was arrested shortly afterward.

'I tried to give them everything'

The letter, addressed to reporter Lou Raguse, was in a white envelope stamped with the words "Mailed from the Polk County jail" and the suspect's name on the top left. It was in response to two previous letters the reporter said he sent to Patterson in jail last month with questions. CNN could not independently verify the authenticity of the letter. Barron County Sheriff Chris Fitzgerald said he was aware Patterson had sent a letter to Raguse, KARE reported.

In the purported letter, Patterson said he had planned to come clean all along after he was arrested.

"I knew when I was caught (which I thought would happen a lot sooner), I wouldn't fight anything," the letter says. "I tried to give them everything ... so they didn't have to interview Jayme. They did anyways and hurt her more for no reason."

'Don't want them to worry about a trial'

He added that he plans to plead guilty to avoid a lengthy trial.

"I want Jayme and her relatives to know that. Don't want them to worry about a trial," the letter says.

Under a question of whether he's remorseful, he describes "huge amounts" of remorse and adds, "I can't believe I did this ... It was really stupid though looking back."

While he was allegedly holding Jayme hostage, the letter says, the suspect followed news updates on the kidnapping on his phone but would change the channel if it appeared on television.

"Would tell Jayme, 'I'm sorry, I can't watch this.' IDK (I Don't Know) what she knew," the letter says.

'I'm Sorry Jayme! For everything'

In the letter, the suspect says he did not tell anyone about kidnapping Jayme and whenever his father visited him on Saturdays, he would hide her in his room. Patterson says he does "not think like a serial killer," and the kidnapping was "mostly done on impulse" and is not something he planned for a long time.

"The reason I did this is complicated," it says followed by an apology in big letters.

"No one will believe or can even imagine how sorry I am for hurting Jayme this much. Can't express it. I'm Sorry Jayme! For everything. I know it doesn't mean much," the letter says.

Law enforcement officers went to the Closs residence near Barron in rural northwest Wisconsin on October 15 after receiving a 911 call from Jayme's mother. They found the parents, James and Denise Closs, shot to death and Jayme missing.

Despite widespread searches, Jayme was not seen for 88 days. When a dog walker found her walking down a road about 70 miles from her home, she was without a coat and gloves in frigid weather.

She said she'd fled the home where she was being held, according to a criminal complaint released by the Barron County District Attorney.

Patterson was arrested moments later and charged with two counts of intentional homicide and a count of kidnapping and armed burglary. Prosecutors said he confessed in detail during an interview after his arrest. He's being held in the Polk County Jail on a $5 million bond. His arraignment is set for March 27.