Jake Patterson confessed to killing James and Denise Closs and to abducting their 13-year-old daughter Jayme, according to the document filed in court in Barron County, Wisconsin.
Referred to in the document by her initials, JLC, Jayme Closs was the subject of a nationwide search following her disappearance three months ago -- until last week when she made a seemingly miraculous escape.
"I did it," the criminal complaint quotes Patterson as saying after sheriff deputies stopped his car in Douglas County, Wisconsin, on January 10.
Patterson appeared in court on Monday by video link from his cell. He showed little emotion as he was formally charged with murder and kidnapping.
The criminal complaint described how he killed the teen's parents on October 15 at their rural Barron home, in order to take their daughter.
He had worked at a cheese factory for two days before quitting. While driving to work on one of those days he had stopped behind a school bus and saw the teen board.
"He had no idea who she was," the document said, but "when he saw JLC, he knew that was the girl he was going to take."
Patterson then allegedly drove twice to her home, hoping to kidnap her, but there were too many cars in the driveway and people visible in the home so he did not carry out the plan.
On October 15 he returned with his father's 12-gauge shotgun, a weapon he chose in part because he felt it "would most likely be the best choice... to kill someone," the complaint says, citing Patterson's confession.
He shaved his face and hair, donned a balaclava and gloves, and had modified his car to carry out the crime.
At the Closs home, he saw James Closs through a decorative glass panel in the front door and shot him dead, the document says.
Killed in front of her
Inside, Patterson found Denise Closs hugging her daughter in the bathtub of the bathroom where they had taken refuge.
He broke the door down after at least 10 hits from his shoulder, bound the girl with duct tape, and then allegedly shot her mother dead.
Patterson told investigators that he had the intention of killing anyone in the house because he could not leave any eyewitnesses.
As he drove with Jayme Closs in the trunk of his car, police cars passed him with flashing lights on their way to her house. Her mother had called 911 before her death.
Patterson then kept the girl captive in his house in an isolated area about 75 miles (120 kilometers) north of Barron.
When he went out or had visitors he forced her to hide under his bed, with totes and laundry bins stacked around and blocked by weights, the complaint says.
The teen told detectives that, under threat of violence, he would make her stay under the bed for up to 12 hours with no food, water or bathroom breaks.
But, last Thursday when he was out, she was able to move the obstacles away and escape, finding help from a neighbor walking a dog.
Patterson was arrested minutes later.