The Indiana dad in the twisted real-life “Orphan” case is speaking for the first time — backing his ex-wife’s claim that their adopted daughter was really an adult with dwarfism who threatened to kill their family.

Michael Barnett spoke to “The Dr. Oz Show” for an episode due to air Tuesday afternoon to discuss Natalia, the girl his family adopted thinking she was a 6-year-old girl from Ukraine but now say was an adult in her 20s.

“It’s obvious that her records were falsified,” he said in a teaser for the episode. “This is an adult masquerading as a child.”

Just like the 2009 movie “Orphan,” Barnett claims Natalia not only tricked them into taking her in — she also threatened to kill their family.

“We took her to the stress center to have her evaluated that she is having thoughts of harming others, and she is stating out loud that she is attempting to kill Kristine,” Barnett said, referring to alleged threats against his ex-wife.

While at the hospital, she started making even more terrifying claims to doctors, therapists and in her notepad, Barnett claimed in a clip given to The Post.

“‘Not only am I trying to kill Kristine, but I’m going to kill the brothers, too. Here’s how I’m going to do it. Here’s what I’m going to do with their bodies,’” he told the show of the alleged threats.

In the teaser, he also said, “She is screaming, ‘I’m going to kill you! You’re going to die!'”

Barnett and his ex-wife, Kristine Barnett, have both been charged with neglect for moving to Canada without Natalia in 2013, when Indiana authorities argue that she was still a child. They are fighting the charges, saying they only left her behind because she was an adult.