A man suspected of kidnapping a Wisconsin teenager and killing her parents is expected to be formally charged Monday, and the charging documents could shed light on what investigators believe the young man knew about his victims, his motives and tactics.

Jake Thomas Patterson , 21, is set to make his initial appearance Monday afternoon in Barron County Circuit Court. Prosecutors are set to formally charge him with two counts of intentional homicide and one count of kidnapping before court begins.

Investigators believe Patterson broke into James and Denise Closs’ home near Barron on Oct. 15, blowing the front door open with a shotgun blast. They say he then gunned the couple down and made off with their 13-year-old daughter, Jayme.

The girl was missing for nearly three months. Police collected more than 3,500 tips but no hard leads emerged.

Then, on Thursday, a woman walking her dog in the town of Gordon, about an hour north of Barron, spotted Jayme on the street. She begged the woman for help, saying Patterson had been hiding her in a nearby cabin and that she had escaped when he left her alone.

But many questions abound. Authorities have said Patterson’s goal the night he broke into the Closs’ home was to kidnap Jayme, but it’s unclear how Patterson became aware of her, especially since he lived an hour away.

Investigators say there’s no evidence of any online interactions between him and Jayme. Her family insists they don’t know the man. Her grandfather , Robert Naiberg, told The Associated Press that Jayme told FBI agents she doesn’t know Patterson at all.

Charging documents in Wisconsin typically contain at least a partial narrative of what happened at a crime scene, as prosecutors try to prove there’s probable cause to support the allegations.

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Details of Jayme’s three-month captivity have not been released, and Barron County Sheriff Chris Fitzgerald has not said whether Jayme was sexually assaulted. But Patterson’s attorneys, public defenders Charles Glynn and Richard Jones, have been lauded for taking high-profile cases with a special emphasis on sexually violent people, according to a state public defender office news release from February 2018.

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Glynn and Jones issued a statement Saturday saying they are relying on the court system to treat Patterson fairly.