Joe Fritz was the attorney for Don Lewis, Carole's deceased husband ... who was last seen in August 1997. Joe tells TMZ ... he's ecstatic the Hillsborough County Sheriff in Florida is looking into Don's disappearance ... on the heels of the immensely popular Netflix docuseries. He says the more attention the case gets, the better.

Fritz wasn't just Don's lawyer before he went missing, he was his friend, and says there's much more to the story -- and he wants to share everything he knows with cops.

So far, he says they haven't contacted him, but if they do, "I would bring them in my home in a heartbeat and offer them a beer."

As we reported ... the Sheriff is hoping to capitalize on the Netflix series about tiger breeders and Baskin, by asking the public for leads in her former husband's case.

For those who haven't seen it ... Lewis was declared dead 5 years after he disappeared, and folks like Joe Exotic believe Baskin killed him. She's denied any wrongdoing.

Fritz tells us he couldn't believe it when he saw the case was getting reopened, but he thanks social media and the 'Tiger King' buzz for making it happen.

He adds that he's not looking for closure. Joe says it's no secret what happened to Don -- claiming he's heard the true story of what went down and accepts it -- but he wants the truth to prevail and justice to be served for his friend.

As for the docuseries ... Joe says it did a pretty good job telling the story of the big cat people, but he thinks it could have spent more time focusing on Don’s disappearance and debunking Baskin's Costa Rica story.