When Michael Barnett and his wife Kristine adopted a six-year-old orphan from Ukraine 13 years ago they believed she had a rare bone growth disorder.
But all was not as it seemed and now the strange story is the subject of a brand new Investigation Discovery documentary - The Curious Case of Natalia Grace.
In the six-part documentary that will air across three consecutive nights, the adoptive parents will tell how she "masqueraded as a child with intent to harm them" in shocking claims.
And the adopted father shares his tell-tale signs that he claims prove their new daughter was actually a 22-year-old woman - claims Natalia herself still denies.
Meanwhile, Michael and his now-ex-wife Kristine were recently acquitted of neglect charges after abandoning her to live alone in an apartment while they moved to Canada.
In the shocking new documentary, the Barnetts allege that Natalia was violent and tried to kill the family after moving into their home.
They claim that she was 22-years-old when they left her - despite her urging that she was just a child at the time.
In 2012, the the family successfully petitioned court to legally change their adoptive daughter's birth year from 2003 to 1989, which in turn changed her age from eight to 22.
And now Michael Barnett has spoken out about the tell-tale signs that he claims prove Natalia was an adult and not a child like she claims.
Speaking in the first episode of the explosive and shocking docuseries, Michael speaks of how he and his wife noticed a few signs within the first months of the adoption.
Recalling the day that they adopted Natalia, Michael said: "We get to the hotel that night, and Kristine’s going to give our brand new daughter a bath, and I hear a shout from the bathroom.
"This was a, ‘I’m not playing around, come here right now, Michael’ shout."
He then explains how he entered the bathroom to see his wife looking completely shocked after she had seen Natalia's unclothed body.
In the episode Michael explains how when he arrived in the bathroom and looked down, Natalia "had full pubic hair", with him adding: "And I don’t know what you think. Is that possible? Is that even possible? Who the f**k is this person?"
Despite the shocking discovery, the couple were keen to make things work and gave their adoptive daughter "love and compassion".
He then recalled how his wife discovered a pair of Natalia's underwear, with a home video then showing the couple asking the girl to explain what had happened.
"I can remember her physical-ness at the time, her hands were just out in front of her like this, and she’s like, 'Well, I have a period, and I’ve been hiding it'," Michael then recalled.
He then went on to explain that it was at this point he began questioning the real age of the orphan.
Natalia has a rare form of Dwarfism called Spondyloepiphyseal Dysplasia Congenita, and has previously denied the claims surrounding the alleged abuse and being an adult at the time of adoption.
Responding to the family's allegations that she was an adult, Natalia spoke to Dr Phil in an interview a couple of years ago when she said: "It's not true. It's not true at all. I just want people to hear my side."
Michael Barnett and his now ex-wife Kristine Barnett were charged in September 2019 with multiple counts of neglect, with him acquitted last fall.
And in March of this year, the charges against Kristina were dropped, according to WTHR.
Meanwhile, Natalia has found a new family and is living with her new adoptive parents Cynthia and Anton Mans and their five children.
The Curious Case of Natalia Grace will premiere across three consecutive nights on ID beginning Monday, May 29, airing nightly from 9-11 pm ET/PT.
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