dean clouse, tina clouse, holly marie clouse

“He really doted over them and tried to make sure that he was able to provide what they needed,” Casasanta tells PEOPLE. “He became a little softer.”

Soon after the move, the letters Dean and Tina wrote home abruptly stopped. The last time anyone heard from them was in late October 1980.

A few months later, Dean’s family received a call from a stranger who said she was in Los Angeles and had information about Tina and Dean as well as a car — a 1978 two-door, red burgundy AMC Concord — she wanted to return in exchange for $1,000.

National Center for Missing & Exploited Children

holly clouse

“She stated that Tina and Dean had joined their religious group and no longer wanted to have contact with their families,” First Assistant Attorney General of Texas Brent Webster tells PEOPLE in this week’s issue. “They were also giving up all of their possessions.”

In January of 1981, the remains of two people were discovered in a heavily wooded area in Harris County near Houston. The man had been beaten, bound and gagged, and the woman was strangled.

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Thirty years later, in 2011, the Harris County Medical Examiner’s office exhumed the bodies to extract DNA to see if they were related.

“Those results obviously showed that they were not kin to each other,” says Misty Gillis, a senior forensic genealogist with Identifinders International.

Gillis says she was looking for a case — " a good fit for forensic genetic genealogy" — on the Doe Network website of unidentified missing and murdered people when she came across the Harris County Does.

“I was absolutely enamored with it because I thought it was like a love story,” she tells PEOPLE. “This man and woman are found together, they’re similar age, you kind of start to think if they’re not related to each other, then what is the capacity they know each other? I wanted to know what the story was.”

With the help from a grant from true crime podcast producersaudiochuck, Gillis teamed up with another forensic genetic genealogist Allison Peacock and began building the family trees of the unidentified couple.

Within days, relatives of Dean and Tina were identified.

“We were able to call [Dean’s] sister and find out, yes, he had been missing for 40 years, and he was married,” says Peacock, founder of FHD Forensics.

“That was the biggest shock I’d ever had in my life,” says Peacock. “We were focused on finding them. It didn’t occur to us they would have had a child.”

And so, the search for Holly Marie began.

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Hope came in January when the Texas Attorney General’s newly formed cold case task force, which was set up to tackle the state’s 20,000 unsolved murders, decided to help investigate the disappearance of Holly Marie.

“We let the world know in December we’re bringing on cases,” Webster tells PEOPLE. “And in January, the Harris County Sheriff’s Office, who does not have a cold case unit, called us up and said, ‘Will you help us investigate this cold case?'”

A few months later, investigators unraveled some of the pieces and announced last week that Holly Marie, now 42, had been found alive.

“They indicated the beliefs of their religion included the separation of male and female members,” Webster says, “practicing vegetarian habits and not using or wearing leather goods.”

According to Webster, there were sightings of the group in Yuma, Arizona. He said the group was known to travel around Arizona, California and possibly Texas.

Last week, law enforcement notified Holly Marie of the identities of her parents and her relatives. She spoke to her biological family members over video conference later that day — on what would have been Dean’s 63rd birthday.

“I first noticed her sweet demeanor, a lot like her mom’s,” says Casasanta, 50. “It was just an amazing thing to find out that she was okay.”

While the family is busy planning an in-person reunion with Holly — who has yet to speak publicly about her life — authorities are still trying to piece together potential evidence of who killed her parents.

“Hopefully somebody will come forward and just tell us what happened and why, and just get it off their chest too,” says Casasanta. “I’m betting that it is even probably eating at them. I don’t really seek redemption over it. I just want to know the answers and everything else will play out how it plays out.”

In the meantime, Casasanta says he wants Holly to know that “her father was a loving, caring person.”

“I just wish that she could have experienced his love and what he was about,” he says. “Unfortunately, she didn’t get that opportunity so that’s a tough thing. And that Tina just really doted over her.”

source: people.com