Man accused of killing former Marengo woman given maximum sentence for abducting daughter from Wisconsin home

A Wisconsin judge on Friday sentenced former Marengo man Jonathan Van Duyn to prison for abducting his biological daughter in what the judge said was an attempt to flee from an Illinois investigation, in which Van Duyn now is charged with killing his girlfriend.

Van Duyn, 34, received the maximum possible sentence in Wisconsin on Friday for interfering with a child’s custody about a month before prosecutors now say he murdered his girlfriend, Michelle Arnold-Boesiger.

The man pleaded guilty Aug. 24 to a charge of interfering with a child’s custody. On Friday, Walworth County Judge Phillip Koss sentenced Van Duyn to a term of 12 1/2 years, 7 1/2 of which Van Duyn will serve in prison. He will complete the remaining five years reporting to the Wisconsin Department of Corrections and adhering to conditions that bar him from having unapproved contact with the girl.

“[Van Duyn’s] personality and social traits are antisocial and frightening,” Koss said in court Friday.

Late last year, police arrested Van Duyn in Indiana and accused him of abducting his juvenile daughter from her home between Dec. 13 and 16 and concealing her whereabouts for several days.

At the time of his arrest, Van Duyn was diagnosed with bipolar disorder and suffering from drug addiction, his public defender, Jenna Proudfit, said in court. Van Duyn was not taking medication for his mental health issues and used fentanyl daily, Proudfit said.

“Things started to get bad when addiction began to pop up,” she said.

Before his sentencing Friday, Van Duyn offered an apology for any pain he caused the girl and her mother.

“I regret my actions on that day,” Van Duyn said. “I look forward to starting my life on a different foot and getting back on track.”

For now, Van Duyn will remain in Wisconsin awaiting an extradition request to have him transferred to Illinois, where he is wanted on a $5 million bond on first-degree murder charges. The Winnebago County state’s attorney said Friday that he plans to file that request next week.

In light of the charges awaiting Van Duyn in Illinois, the Walworth County judge questioned some of the comments that Van Duyn made in a pre-sentence investigation report. Specifically, Van Duyn claimed that abducting his daughter was the most serious act he’d ever committed, the judge said. Koss, however, challenged that assertion, citing the out-of-state murder allegations against Van Duyn.

“This isn’t just done in isolation,” Koss said of the abduction.

Wisconsin police began their initial investigation the morning of Dec. 13, after the girl’s mother called police to her home at 7:14 a.m. to report that her daughter was not at home and was last seen at 8 p.m. the previous day, Wisconsin court records show.

The girl, then 10 years old, appeared to have taken her cat and $30 with her but not her coat, court records show.

An Amber Alert was issued for her that morning.

Days later, on Dec. 16, investigators found Van Duyn and his daughter safe in a remote area in Indiana. The pair had been traveling in Arnold-Boesiger’s truck and staying in a trailer, according to Winnebago County court records. The campsite where they were found was reserved under Arnold-Boesiger’s name with an email address that referenced one of Van Duyn’s aliases, “Kyle,” court records show.

Attorneys said in court Friday that Van Duyn was on his way to Florida with the girl. A pre-sentence investigation report additionally claimed that Van Duyn talked to his daughter about taking their lives when they arrived, attorneys said in court.

“This was an extremely serious case,” Walworth County Deputy District Attorney James Sempf said.

Proudfit told the judge Friday that Van Duyn disputes the allegation that he spoke with his daughter about taking their lives.

Reached by phone Friday morning, the girl’s mother said Van Duyn’s sentence brought her a sense of relief.

“She worried for her own life,” the mother said. “She didn’t think that she was going to come back. For her, it was very traumatic.”

Days before Van Duyn abducted his daughter, he allegedly told a family member that he was going on “an epic journey,” according to court documents.

Investigators who searched the camper where Van Duyn and his daughter were found also discovered writing on the walls and in one of Van Duyn’s journals that referenced Nov. 15, 2020, as the day he “was finally free,” according to court documents. Prosecutors in Winnebago County have since said they think Nov. 15 is the same day Van Duyn killed Arnold-Boesiger.

“This isn’t an ‘epic journey’ to enjoy a weekend at Disneyland,” Koss said in court Friday. “This is escaping a homicide investigation.”

Van Duyn awaits a series of charges in Illinois tied to Arnold-Boesiger’s death and disappearance.

The Winnebago County state’s attorney announced first-degree murder charges against Van Duyn in August, although it was not immediately clear Friday when he might be brought back to Illinois.

[ Timeline: The death and disappearance of Michelle Arnold-Boesiger ]

After his arrest in Indiana, Van Duyn told police that he drove to the girl’s home Dec. 12 and picked her up just before midnight. He then drove them to University Park to stay in his trailer, court records show.

When Van Duyn began receiving calls inquiring about the girl’s whereabouts, he destroyed both of their cellphones and threw them in a dumpster to avoid being tracked, according to a criminal complaint filed in Walworth County. He then drove to the campsite in Indiana and barred his daughter from leaving the trailer.

Prosecutors have since alleged that Van Duyn killed Arnold-Boesiger about a month earlier and hid her body in his Jeep Renegade, which he then stored inside a U-Haul unit in Roscoe, Illinois.

Investigators found Arnold-Boesiger’s body months later on March 2. Her body was partially mummified by the time police found her, and officials have not released a potential cause of death.

Those who knew Arnold-Boesiger have described her as kind, a loving mother and “a sweetheart” who loved dogs and saw the best in people.

Her family has asked for privacy since the murder charges were filed in Winnebago County.