Secrets Of Palm Beach

A Socialite's Secret Love Life Leads To Murder

(CBS)  And Kretzmer probably would have remained a secret, if not for the anonymous letter written by a former girlfriend of his, Gissele Ospina.

"I heard that night February 6, 2003 a man named Frederick Kretzmer was driving her car and had a few pieces of her jewelry…I do not have any proof. I just want to point you in the right direction," the letter read.

"You have that feeling inside that it's the right thing to do. It's not something that you can, you know, so I wrote the letter," Ospina told Roberts, speaking publicly for the first time about her difficult decision to tip off police.

The letter, Keith says, was critical. After four months of dead ends it finally gave detectives a red hot lead into who might have killed Linda.

"So basically we start peeling back the onion on Fred Kretzmer," Keith says. "Fred had a troubled childhood, had some possible molestation issues when he was younger. Some possible alcohol abuse in his family. He had some substance abuse issue with cough syrup and other drugs. At some point I think he came to Florida to try and distance myself."

A man named Mario Segura became close to Kretzmer when they worked together after Kretzmer moved from New Jersey to Florida in the mid 1990s. He quickly fit in with Mario's family and friends, which is how he met Gissele

Kretzmer made ends' meet through various odd jobs, including working as a maintenance man at a Marriot hotel. Police learned it was there that Linda met him in 1999, when she and her sister Bernice stayed for a weekend arts festival.

"And see, I went back up to the room around 10 or 11. She went down to the cocktail lounge, and I don't know, maybe she met him down there later," Bernice remembers.

Later that night, Bernice woke to Kretzmer knocking on their door. Asked what he said, Bernice says, "Nothing, he just says, 'Is Linda there?' That's all. And I said, 'No, she's sleeping.'"

Bernice had never seen Kretzmer before, nor did she know Linda would continue a relationship with him.

"I think he was probably using her. She was vulnerable because she was a lonely person. And, you know, open to that," Keith says.

By 2001, Linda and Kretzmer's relationship had fizzled out. He was still working odd jobs, when Mario urged him to leave Florida and join the Navy.

But just seven months into his service, while stationed in California, Kretzmer's life went off track when he was arrested after a high speed chase with a police officer and charged with being under the influence of controlled substance, resisting an officer, drunk driving and petty theft.

Kretzmer was discharged from the Navy and served eight months in a California state prison. To his friends back in Florida, Kretzmer seemed to have just fallen off the map, until the winter of 2003 when he called from New Jersey to say he was coming for a visit.

Gissele says Kretzmer looked like a "different human being" to her. "You know that look that someone has when someone hasn't slept for days or taken a shower or something. Dirty, like tired," she recalls.

Kretzmer's personality had changed dramatically as well. He was withdrawn and appeared troubled, even telling Gissele he was hearing voices in his head