GRAPHIC: Probable Cause hearing for Idaho Falls murder suspect Brian Mitchell

WARNING: The story contains graphic details of a violent and sexual nature. Some viewers and readers may find the content disturbing.

IDAHO FALLS – Moments after he allegedly killed Deraek Larson, 18-year-old Brian J. Mitchell ran to his father’s Idaho Falls home and told him he had “really messed up” and was “going away for a long time.”

That’s according to 50-minute audio recording EastIdahoNews.com obtained of Mitchell’s probable cause hearing. During the hearing, Idaho Falls police detective Josh Deede was questioned by Bonneville County Prosecutor Danny Clark. He recounted what Mitchell told him during interrogation after the Shelley native was arrested early Thursday morning.

Mitchell has been charged with second-degree murder for allegedly killing Larson on a playground structure at Tautphaus Park. Police said Larson was stabbed more than 20 times with a knife. Larson was found dead by a passerby the morning of Sunday, Aug. 16.

Authorities cannot comment on events described in the recordings as the testimony is part of an ongoing investigation.

Deede told Clark and Magistrate Judge Jason Walker that Larson had been kicked out of his home by his brother’s roommate around 1 a.m. Saturday.

Larson met Mitchell, a man and a 16-year-old boy who were in an SUV at a KeyBank in Idaho Falls. The men invited Larson inside so he could stay warm. It is unclear from the recording if Larson knew any of the men in the SUV.

The men fell asleep in the vehicle, Deede said. When they woke up, they drove around Idaho Falls all day Saturday. Mitchell, Larson, the man and the teenager eventually ended up at Tautphaus Park.

“They were just hanging out at one of the shelters consuming alcohol that had been purchased earlier in the day,” Deede said, adding the trio were drinking vodka.

Clark asked Deede if the group discussed sexual activity.

“Brian and Dereak started talking about how they preferred their oral sex and who (what genders) they preferred their oral sex with,” Deede said.

Deede said Mitchell and Larson then told the teenager to leave the park, telling him to “kick rocks.”

“As (the teenager) was leaving, he received a hug from Deraek and a kiss on the neck from Deraek that made him feel weird,” Deede said.

At this point in the narrative, Deede said, it was dusk and Mitchell fell asleep on a picnic table bench. Mitchell told investigators that when he woke up, Larson was performing oral sex on him.

“(Mitchell is) startled by this and he said he was not into that,” Deede said. “(Mitchell) said he wasn’t sure why Dereak would do that. Deraek tells Brian that they were talking about it earlier, and Brian said he was OK with this, so it shouldn’t be a big deal.”

Mitchell then left the shelter and walked to a nearby playground, Deede said. He then fell asleep inside the circular tube section of the playground structure.

When he awoke, Mitchell told detectives, Larson was on top of him wearing only boxer shorts. Mitchell told police Larson was trying to pull his pants down and that he said to Larson, “Knock it off. If you don’t, I’ll hurt you. Knock it off.”

A struggle then ensued inside the circular tube and, according to Deede, Mitchell pulled out a knife and stabbed Larson between the eyes. Mitchell proceeded to stab Larson more than 20 times, Deede said, and some of the wounds were so forceful that Larson received brain injuries and a skull fracture.

After the attack, Deede said Mitchell ran from the park to his father’s home in Idaho Falls.

“He was wearing dark pants, and his concern was he had blood on his shirt,” Deede said. “He had taken his shirt off and slipped it inside out so when he met his father, his shirt was on the inside out to try to conceal anything that would cause his father’s suspicion.”

Detectives said Mitchell told his dad he had “really messed up” and was going away for a long time. Mitchell’s father then took his son to a grandparent’s house in Shelley. Mitchell showered and allegedly put his bloody clothes into a plastic bag.

“The next day he walked down to the river near Shelley and threw the bag of clothing into the river,” Deede said.

Deede did not reveal who or what tipped police off onto Mitchell and the recording does not mention if Mitchell has confessed to the crime.

The detective said Mitchell’s story has changed over the course of questioning.

“He initially said he was not involved in oral sex and he’s not that way,” Deede said. “(But) later on he changed his statement and said he may have agreed to it, but only while he was sleeping.”

Detectives discovered a small cut on Mitchell’s right hand that he said he sustained as his hand slipped on his knife.