The family of "Tiger King" subject Carole Baskin's first husband, who mysteriously disappeared in 1997, is offering $100,000 in exchange for information about what happened.

Attorney John Phillips held a news conference in Tampa, Fla., on Monday and announced an independent investigation into the disappearance of Jack "Don" Lewis. He also said that on behalf of the Lewis family, he's filed a lawsuit against Baskin in an attempt to depose her and get her to speak on the record. He and the family have also paid for Tampa-area billboards asking for information in the case.

Lewis' case, and Baskin, were featured in the popular Netflix documentary series "Tiger King: Murder, Mayhem and Madness." The show followed Joseph Maldonado-Passage, also known as “Joe Exotic,” an eccentric former Oklahoma zookeeper who loves big cats.

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Earlier this year, Maldonado-Passage was sentenced to 22 years in prison for his role in a murder-for-hire plot. He was convicted of trying to hire someone to kill Baskin, who had tried to shut him down, accusing the Oklahoma zoo of abusing animals and selling big cat cubs.

'Tiger King' subject Joseph Maldonado-Passage, also known as Joe Exotic, previously accused Carole Baskin of murdering her ex-husband. 

'Tiger King' subject Joseph Maldonado-Passage, also known as Joe Exotic, previously accused Carole Baskin of murdering her ex-husband.  (Netflix)

In retaliation, Maldonado-Passage raised questions about Baskin’s former husband. The documentary extensively covered Maldonado-Passage’s repeated accusations that Baskin killed her husband and possibly fed him to her tigers. Baskin hasn't been charged with any crime and has repeatedly released statements refuting the accusations made in the series.

Lewis vanished a day before a scheduled trip to Costa Rica and was never found. He was declared legally dead in 2002. He and Baskin started the animal sanctuary, which later became Big Cat Rescue Corp. in Tampa.

Three of Lewis’ daughters were at the news conference. Lewis’ youngest daughter, Gale Rathbone, expressed gratitude for those interested in the case.

“Amazingly, our little family tragedy has become your tragedy. Our search for closure and truth has become your mission also,” she said. “We all know by now that (Lewis) was not a perfect man. But do only the perfect among us deserve justice?”

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In an email sent to the Associated Press Monday, Baskin said she wouldn't comment. “It’s been my policy not to discuss pending litigation until it’s been resolved," she wrote. “I had told some news outlets that I thought the press conference on Aug. 10 was just a publicity stunt, but at that time was not aware there would be pending litigation.”

Carole Baskin, founder and CEO of Big Cat Rescue, is the subject of a new lawsuit having to do with the disappearance of her former husband.

Carole Baskin, founder and CEO of Big Cat Rescue, is the subject of a new lawsuit having to do with the disappearance of her former husband. (Netflix)

Baskin is still the owner of Big Cat Rescue, and lobbies for abolishing private wildlife ownership.

Maldonaldo-Passage is currently in prison. A federal judge in June granted control of the Oklahoma zoo that was previously run by Maldonado-Passage to Big Cat Rescue Corp.

Baskin previously sued Maldonado-Passage for trademark and copyright infringements and won a $1 million civil judgment against him. The judge found that ownership of the zoo was fraudulently transferred to Maldonado-Passage’s mother in an attempt to avoid paying the judgment.

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In March, the Hillsborough County sheriff asked for tips in the case of Lewis and announced a reopening of Lewis' case.

The Associated Press contributed to this report.