Charges: 18-year-old stabbed 14-year-old ex-girlfriend 13 times, left body near the river

An 18-year-old Fargo man has been charged with second-degree murder in connection with the killing of 14-year-old Jaelyn Walker.

Isaac Arthur Arndt was arrested and booked into Cass County Jail. Authorities are working to extradite him to Clay County.

Authorities are asking for the public’s help to find Arndt’s cell phone. On Wednesday, they said the Samsung Galaxy cell is believed to be in Fargo between the blocks of 2nd Avenue South to 10th Avenue South between 15th Street South and 23rd Street South.

According to a criminal complaint, Walker’s mother reported the 14-year-old missing around 12:35 a.m. Tuesday. She had tracked her daughter’s location via SnapChat to a bike trail near the intersection of Elm Street and 6th Avenue South.

Officers found Walker’s body in the Red River in a wooded area along a trail. Court documents state she had been stabbed several times and a knife was found at the scene.

Hours before Walker was reported missing, charges say that Arndt went to the Clay County Law Enforcement Center to report being assaulted. He told police that he was with Walker at Gooseberry Park when a man started following them.

He said he and Walker were on a scooter, but he ran from the area, and the man cut him on the hand with a knife. Court documents state he had cuts on his fingers.

After finding Walker’s body, police spoke with Arndt again. According to court documents, he changed his story several times when explaining what happened between him and Walker that night.

Arndt later admitted that he and Walker had been in a relationship for several months, but it had recently ended. He told police Walker wanted to know who his new girlfriend was but he refused to tell her.

Arndt then claimed that Walker started to hit and kick him, leading to him stabbing her about 13 times. He said he then left the scene on his scooter and discarded his phone and backpack before abandoning the scooter.

Court documents state that Arndt’s backpack and scooter were found in the places he described, but the phone wasn’t found. Arndt’s wallet was also found near the scene.

Arndt said he then went to his apartment in Fargo, where he cleaned up and washed his clothes, which were covered in blood.

During a search warrant execution of his apartment, officers found socks, a towel and a lot of toilet paper with red stains, according to court documents.

Surveillance video showed Arndt walking away from the path where Walker’s body was found. The video also showed Arndt discarding items near where Walker’s phone was found.

Officers found messages between Arndt and Walker agreeing to meet at Gooseberry Park. A witness also reported seeing them on a scooter at the park.

In another interview with police, Arndt admitted that Walker was not alive when he left the scene.

Arndt told police that he stabbed Walker several times and noted she was lying there suffering. According to court documents, he said he then cut her throat, hugged her, and then stabbed her once more in the back.

He then told police he dragged her body to the river and fled the scene.