He persuaded school employees in Princeton, West Virginia, to release 16-year-old Louise Robinette to him without her parents' knowledge, two of her siblings told the Mail Online.
David and Louise’s 13 children are alleged to have kept their 13 children chained, shackled and locked inside their Californian home in horrific conditions.
The pair have been charged with 75 counts including torture, false imprisonment, child abuse and abuse of dependent adults. David Turpin, 57, also faces a charge of lewd acts with a minor. They are each being held on US$13 million bail and deny all charges.
The couple’s children range in age from two to 29.
Louise's younger sister and half-brother, Teresa Robinette and Billy Lambert believe neither David nor Louise should ever leave prison.
'I hope they suffer as much, if not more, than those kids suffered,' Teresa said in their extensive, exclusive joint interview.
'I hope they torture my sister for the rest of her life.
'I have four siblings now instead of five,' she added. 'She is off my family tree, she is dead to me. I couldn't care less about speaking to Louise ever again.'
And Billy Lambert added: 'I think they should get a life. That's not just spur-of-the-moment anger, I'm not changing that view.'