SALT LAKE CITY (ABC4 Utah) – Nearly three decades later, Frank Frost finally met someone who might know what happened to his sister.

“I was skeptical at first,” said Frank Frost.

The conversation set up by police was the first time Frost had information about his sister, Debbie Frost.

In July 1984 she was 17-years old and was walking home from her boyfriend’s house. She walked through downtown Salt Lake City.

The teen suddenly disappeared and no one heard from her again.

Frank Frost was only six years old when she vanished.

“I was aware something happened,” he said. (I knew) that Debbie was gone, and they were looking for her.”

Soon the public learned of her disappearance. Police told the media that Frost “never arrived home” that night. They considered “foul play” and was not a runaway because “she’s happy and planning a birthday party for her boyfriend.”

“She had run away a couple of times before, but she had always been in contact with her dad and her aunt,” said Frost.

She never returned home. As a ten-year-old, the brother badgered Salt Lake City police for answers. He sought media attention but got none.

The years passed and her disappearance turned into a cold case.

Frost said in 2011, a new detective took over and started looking at unsolved murders and disappearances in Salt Lake City. Debbie Frost was amongst those.

“She got me on some news outlets and put me on air and we got some leads,” said Frost.

In 2012, police confirmed the case was re-opened following a tip.

Authorities told the media that Frost had “gone to Rock Springs” Wyoming after her disappearance. News reports said Frost has a run-in with police “July 21, 1984.” It was two weeks after she was last seen in Salt Lake City.

A man who wishes to remain anonymous was the one who provided the tip to Salt Lake City police. He knew about Frost being in Rock Springs. That’s because his friend Fred Martinez was trying to strike a relationship with Frost.

“She hung out, her and her friends hung out with Fred for about a year,” said the friend. “They’d come over the house and do drugs with us and party. Sometimes they’d clean his house for drugs or money.”

It appeared Debbie Frost was a close friend of Martinez while she was living in Salt Lake City. Martinez lived in Salt Lake and his family was from Rock Springs and still returned there from time to time according to the friend.

“I think he was grooming her the whole time because he had a crush on Debbie,” said the friend. “I think he was grooming her.”

Friday, on Missing in Utah, Frost attempted to hitchhike back to Salt Lake City.