Image copyright Abducted in Plain Sight/Top Knot Films Image caption Robert Berchtold was close to Jan and her family

Jan Broberg's nightmare began when she woke up with her arms and legs tied to a bed, and a tape recorded voice speaking to her. She was 12 years old.

"I thought I'd been taken by a UFO," she says.

"I was more terrified of that voice and those messages coming from that voice, than probably anything else that happened to me," Jan recalls, speaking to BBC Radio 5 Live.

In the early 1970s, Jan was kidnapped from her home in Idaho by a convicted paedophile who not only groomed her, but her entire family too. Her story is told in the Netflix documentary Abducted in Plain Sight.

Robert Berchtold was a friend of the Broberg family. A churchgoer and a pillar of the community, he made the family feel special.

When Jan was kidnapped, her parents couldn't believe Berchtold meant her any harm.

"They called the sheriff's department that night that we did not come back from horseback riding, or at least that's where they thought we had gone. But they weren't looking for a kidnapped or missing child. They were looking for a car accident," Jan says.

But their daughter had been taken thousands of miles away to the Mexican desert and drugged.

Jan woke up in Berchtold's motorhome. Tape recordings told her that aliens were now in charge, and she should meet a man and have a child with him in order to save the planet. Jan says she believed everything she heard.

"The message said 'You will go to the front of the motorhome and meet the male companion.' They'd been calling me 'the female companion' this whole time. I get up, and who's lying on the little sofa of the motor home? Robert Berchtold."

Incredibly, Berchtold would use this elaborate story to control and brainwash Jan for the next four years.

"I literally did anything [the aliens] told me to do," she explains, "because they told me my little sister would be taken if I didn't fulfil the mission of having the child for their dying planet."

Image copyright Abducted in Plain Sight/Top Knot Films Image caption Bertchtold manipulated the whole family

After five weeks, the FBI tracked Jan and Berchtold down. But Jan was too scared to tell anyone about the aliens, and too scared to disclose that she had been abused.

"My dad did not ever let Berchtold back in our house, back into his life," she says. "He knew something was totally wrong with him. But [my dad] didn't know that he'd molested me or raped me because I wasn't telling."

Berchtold only served a few days in jail for kidnapping Jan. In the months before her kidnap, he'd persuaded both her mother and father to have sex with him. That meant he could blackmail both of them into signing affidavits to show he had consent to take Jan to Mexico.

Berchtold returned to the neighbourhood, and continued to see and control Jan.

Revelation

The abuse and the alien story became part of Jan's life until she went to a summer camp as she approached her 16th birthday. Until then she had avoided boys.

"Basically I had all these rules that I was supposed to follow that had been given to me from the aliens," she says. "I couldn't have anything to do with boys. If I did, my family would die."

So when a boy bought her an ice cream, she panicked and phoned home. Everyone was fine.

"It was enough for me to start testing the waters," says Jan. "Over the course of the next two-and-a-half months I would test little things - I would talk to a boy at school and I accepted a date to the homecoming dance…

"I knew if I came home from that date and my dad wasn't dead and my sister wasn't kidnapped or missing and my other sister Karen wasn't blind, and Mom and I weren't evaporated, then it wasn't real. And that's what happened."

Image copyright Abducted in Plain Sight/Top Knot Films Image caption The Broberg girls in 1977

Slowly she felt able to tell her family what had been happening to her - how she had been brainwashed and abused by a man the family had thought was a great friend.

"I wasn't able to talk definitively or explicitly about the sexual abuse. It was really hard for me to do."

When Jan tells her story of years of abusive control, it seems hard to believe her parents hadn't spotted what was really going on.

"I don't think they had any inkling at all. I mean literally, that was just not at all possible, because of the amount of love he had showered on the family."

Healing

Over the next decade, Jan slowly disclosed what had happened to her, sought counselling and rebuilt her life. Berchtold disappeared, returning almost three decades later; turning up and harassing Jan at public speaking events.

Image copyright Abducted in Plain Sight/Top Knot Films Image caption Jan told her story as part of a documentary

Jan brought stalking charges against him, and finally faced her abuser in court. But he killed himself before he could be sentenced. Berchtold only served 15 days for the rape and abuse of Jan, and for subsequent abuse of other youngsters.

Jan is still speaking out, reminding people to look for abusers who hide "in plain sight".

She wants people to trust their gut "and keep looking, instead of turning away".

Jan says she hopes after hearing her story, other survivors will feel "empowered to move forward with their own life and to fix what's broken" after hearing her story.

Listen to Jan Broberg being interviewed on BBC Radio 5 Live.