The family of a Canadian filmmaker and conservationist who died during a shark filming excursion in the Florida Keys has filed a wrongful death lawsuit.

The lawsuit filed Tuesday in Broward County, Florida regarding the death of 37-year-old Rob Stewart accuses the companies and individuals who organized the January dive of negligence.

Among them is Peter Sotis, the famed diver who was with Stewart when the filmmaker disappeared, and who has a checkered legal past.

Sotis pleaded guilty to robbery in 1991 and served three years in federal prison for his role in a $308,000 jewelry store heist, news archives show. More recently, a former business partner accused Sotis of selling 'military-grade' re-breather equipment to a Libyan militant, according to court filings.

The family of filmmaker Rob Stewart (left) is suing for negligence in his January death on a dive in the Florida Keys. Famed diver Peter Sotis (right) is among those named in the suit

Stewart, of Toronto, Canada, was diving with Sotis off the coast of Islamorada, Florida when he disappeared in January

The fatal dive took place while Stewart was working on a follow-up film to his 2006 documentary, Sharkwater, which examined the impact of shark hunting

Sotis' company, Add Helium, was also named in the suit, and made the re-breathers used on the dive.

'When you learn more about these defendants and the history of negligent behavior by people like Mr. Sotis, you come to realize this was a preventable tragedy that was going to happen to someone,' Michael Haggard, lawyer for the Stewart family, said in a statement to the Miami Herald.

Stewart, of Toronto, Canada, was diving with Sotis off the coast of Islamorada, Florida, to film a follow-up to his 2006 documentary Sharkwater, which examined the impact of shark hunting on the ocean's ecosystem.

Sotis and Stewart were investigating the wreck of the Queen of Nassau on January 31 when, the suit claims, they took three dives to the wreck using re-breathers, which extend the length of a dive by scrubbing carbon dioxide from recycled air.

Experts consider that amount of diving with re-breathers pushing the envelope of safety.

The suit claims Stewart and Sotis surfaced together, but said that when Sotis experienced difficulty breathing, Stewart disappeared while dive organizers were focused on treating the other man.

Unspecified damages are being sought by the lawsuit.

A massive manhunt ensued after Stewart went missing, with family and friends holding out hope as rescuers searched a 6,000 square-mile area over three days.

A massive manhunt ensued after Stewart went missing, with family and friends holding out hope as rescuers searched a 6,000 square-mile area over three days

After searching an area the size of Connecticut, rescuers found Stewart's body 300 feet from where he disappeared

'If anybody can survive in the water, it is him,' Brian Stewart, his father (left) had said in a telephone interview at the time. Mother Sandy Stewart is shown right

'If anybody can survive in the water, it is him,' Brian Stewart, his father had said in a telephone interview at the time, adding his son was 'super fit' and a highly skilled scuba diver.

'A bunch of the people in the boat gave their attention to a guy who collapsed and a minute later they turned, and Rob was gone,' he said.

About an hour after the Coast Guard suspended the search, Stewart's body was found just 300 feet away from where he'd disappeared, 220 feet underwater.

The U.S. Navy, Customs and Border Protection, Florida wildlife officials, a county sheriff's office and civilian volunteers had joined the Coast Guard in the search, which covered an area about the size of Connecticut.

Ships, helicopters, airplanes, dive teams and sonar equipment were deployed in the effort, the Coast Guard said.

Rob Stewart's 2006 documentary Sharkwater was aimed at exposing the shark hunting industry that was feeding demand for fins, a delicacy in Chinese cuisine

Stewart said his new film was looking at other ways that as many as 80 million sharks were being harvested each year for items ranging from cosmetics to pet food

Rob Stewart's 2006 documentary Sharkwater was aimed at exposing the shark hunting industry that was feeding demand for fins, a delicacy in Chinese cuisine.

The hunting has ravaged shark populations and the film was part of a campaign that helped persuade some governments to crack down on 'finning'.

With finning, typically the fins are cut off and the live shark is tossed back into the sea. Unable to swim properly, the shark suffocates or is killed by predators.

Stewart said his new film was looking at other ways that as many as 80 million sharks were being harvested each year for items ranging from cosmetics to pet food.

'Sharks are sophisticated, intelligent and often shy creatures that aren't interested in eating humans,' he said in a video seeking funding for his new movie.