Media playback is unsupported on your device Media caption Jayme Closs was found alive by a woman walking her dog

A Wisconsin man accused of killing a 13-year-old girl's parents so he could kidnap her allegedly made up his mind to snatch her after a chance encounter.

Jake Patterson, 21, told investigators he watched Jayme Closs board a school bus that he had stopped behind while driving to work.

He was formally charged on Monday with killing Jayme's parents and kidnapping her on 15 October last year.

Jayme escaped last Thursday after three months in captivity, say police.

ADVISORY: Some readers may find details in this story upsetting.

On Monday, a criminal complaint outlined how Mr Patterson came up with the idea of targeting Jayme.

He allegedly told investigators he was driving to his job at a cheese factory one day near the village of Almena when he spotted Jayme get on a school bus.

The charging document quotes Mr Patterson as saying that when he saw Jayme, "he knew that was the girl he was going to take."

What is he accused of?

Mr Patterson told police he only had worked at the factory for two days, and ended up spotting Jayme on one of the two mornings he drove to work.

The complaint says the accused twice scouted the Closs home near Barron with the plan of taking Jayme.

Image copyright Jennifer Smith Image caption Jayme Closs, her aunt/godmother Jennifer Smith and Molly the dog posing together after being reunited on January 11

But he abandoned the plot those times because too many people were in the vicinity.

Mr Patterson described the measures he took to avoid detection, including shaving his head, stealing a license plate, wiping the shotgun with gloves on and modifying his car boot so it could not be opened from the inside.

The charging document says that when Mr Patterson eventually stormed the family home by the front door, Jayme and her mother, Denise Closs, took refuge in the bathroom.

The pair heard a gunshot and suspected the home-invader had killed the father, James Closs.

Image copyright AFP Image caption Police say the suspect took steps to conceal his identity

Mr Patterson allegedly broke down the bathroom door, and forced Denise Closs to help bind Jayme's hands and ankles with tape before shooting her.

He then dragged Jayme to his car and threw her in the boot, according to the criminal complaint.

Jayme told investigators that Mr Patterson drove 66 miles (105km) to a rural cabin near the small town of Gordon, where she was allegedly held until her escape.

Once at the Gordon home, Jayme said that Mr Patterson took all of her clothes, saying he would throw them away.

She told police he would sometimes make her hide under his bed when friends or family visited the cabin, making it clear "that nobody was to know she was there or bad things would happen to her".

Sometimes, Mr Patterson "would make her stay under the bed for up to twelve hours at a time with no food, water, or bathroom breaks", according to the complaint.

And to ensure she was trapped, Jayme told officials he would stack containers with heavy weights around the bed "so she could not move them without his being able to detect it".

How did Jayme escape?

On 10 January, Jayme said she was able to escape after Mr Patterson left the house, informing her he would be out for five or six hours.

She told police she was able to move the weights and crawl out of the room. She took a pair of Mr Patterson's shoes and fled on foot, eventually encountering a neighbour who helped her contact police.

According to the local officers who then arrested Mr Patterson, when he stepped out of his vehicle "he stated 'I know what this is about'", adding "I did it".

Media playback is unsupported on your device Media caption Missing girl praised for 'courageous' escape

After his arrest, Mr Patterson told investigators he assumed he had got away with the murders and kidnapping after two weeks, the complaint states.

He added that he only learned of Jayme's name after abducting her and Mr and Mrs Closs' names weeks later after seeing them on television.

Mr Patterson told police "he never would have been caught if he would have planned everything perfectly".

A judge ruled that the suspect must be held on a $5m (£3.8m) cash bond pending trial during a court hearing on Monday. The next court hearing is scheduled for 6 February.

Authorities have yet to reveal any suspected motive.

His father and brother cried during the 10-minute court hearing. As they left the courtroom, his father shook his head when asked by a reporter if he know what had been going on in his home.

Image copyright Pool Image caption The suspect appeared in court via a video feed from jail

While Mr Patterson himself had no criminal record in the state, his older brother, Erik, was convicted of fourth degree sexual assault in 2013 for having sex with a 16-year-old girl when he was 18.

Former classmates of Mr Patterson's told the Milwaukee Journal Sentinel he was voted the quietest student in his grade one year and never made an impression.

'A happy ending to such a horrible beginning'

After 88 days, Jayme is now in the care of her aunt, Jennifer Smith, and has been reunited with other family members.

Speaking on CBS This Morning, Jayme's aunt Lynn Closs said: "It's such an overwhelming, amazing happy ending to such a horrible beginning."

Another aunt, Sue Allard, said she finally "didn't have that pit in the bottom of my stomach anymore".

She said the family has not pressed her for any details of her experience.

"She feels safe. She's doing pretty well. I spent the afternoon there yesterday. We had her smiling, laughing."

"We have to take little steps. Jayme, when she's ready to talk, she will."

Her aunts say they will attend all of Mr Patterson's court proceedings.

"I want him to know that he messed with us as a unit, and that good wins. And that is not him," Ms Closs added.