Moorhead, MN (Valley News Live) – A search warrant filed in Clay County District Court states that 18-year-old Isaac Arndt went to the Clay County Law Enforcement Center shortly after 11 p.m. on Monday, August 19 and asked to report an assault.

That night, Arndt told a police officer he was with 14-year-old Jaelyn Walker at Gooseberry Park in Moorhead when a man they did not know began chasing them. Arndt told police he and Walker were on an e-scooter but stopped to see what the man was doing. Arndt reported Walker ran away when the scooter was stopped and the man stabbed Arndt. The officer took photos of Arndt’s hand, which had two cuts on the fingers. Arndt went to a local hospital for his injuries.

The warrant states that Walker’s mother filed a missing person report with Moorhead police at approximately 12:35 a.m. on Tuesday, August 20. The mother told police she followed her daughter’s whereabouts via SnapChat to an area near a bike path at Elm Street and 6th Avenue South in Moorhead. According to police, several officers were called to search the area and Walker was found in the Red River in a wooded area along the trail. Police said they found a knife and blood at the location. Police said Walker suffered significant sharp object injuries to his back, torso and neck.

Police later tracked down Arndt at a local hospital. The warrant states that Arndt retold his original story to investigators, but then expanded on it with a number of different versions of what happened. One example from the warrant is that Arndt was able to point to a map showing exactly where Walker could be found.

Upon further questioning, Arndt eventually admitted that he and Walker had been in a relationship for several months but had recently broken up. Arndt told investigators that Walker had asked him who his new girlfriend was, but when he wouldn’t tell her, she began punching and kicking him. Arndt says he then pulled a knife from his pocket and began stabbing Walker. Arndt admitted that he stabbed Walker about 13 times before riding away on his scooter. The warrant states that Arndt left his scooter, backpack, and phone behind. The scooter and backpack were found, but his phone was never found.

Arndt told investigators that after leaving the Moorhead area, he went to his Fargo apartment, where he cleaned and washed his blood-stained clothes. A search warrant was later executed for Arndt’s apartment, where investigators found socks and a towel with red stains hidden in a kitchen cabinet.

The warrant describes that video surveillance from a nearby home showed Arndt leaving the wooded area in Moorhead where Walker was found. A search of Walker’s phone shows messages between Arndt and Walker in which they agreed to meet at Gooseberry Park around 7:30 p.m. Detectives say while investigating the crime scene, Arndt’s wallet was found in the area.

Later that day on August 20, investigators went back to the Cass County Jail to speak with Arndt. Investigators say that during that conversation, Arndt admitted that he knew Walker was not alive when he left the crime scene. Arndt told investigators that he stabbed Walker several times, then slit her throat, hugged her, and stabbed her in the back once more. Arndt says that afterward, he dragged her body to the river, where he left it.

Arndt is charged with premeditated murder. You can read previous reports here.

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