A diver who was with famed Canadian documentary filmmaker Rob Stewart when Stewart slipped beneath the waves Jan. 31 after ascending from a deep-water dive off Islamorada — and was found dead three days later — is a defendant in a bizarre lawsuit with his former business partner in which he’s accused of selling military-grade scuba gear to a Libyan militant last August.

Peter Sotis, a well-known name in the rebreather diving community, is being sued by Shawn Robotka, a Key Largo man who owns 20 percent of one of Sotis’ businesses called Kaizen International Solutions LLC. Robotka wants a judge to liquidate Kaizen’s assets and grant an injunction preventing Sotis from continuing to operate the business.

Among other arguments, Robotka’s attorneys wrote in a Dec. 22, 2016, complaint filed in Broward County Circuit Court that Sotis sold rebreather and underwater propulsion equipment to a client in Libya. Robotka argues that violates federal law and subjects him and Kaizen Solutions to liability. Robotka’s attorneys state in the complaint that the sale in August 2016 was executed after federal agents with the U.S. Department of Commerce, Homeland Security and FBI cautioned the transaction was against the law.

It’s unclear whether that sale actually happened or if Sotis is under any sort of investigation. His attorney, Raymond Robin, said he doesn’t know.

“They’re the ones claiming it, so I would ask them,” Robin said of Robotka’s attorneys, Robert Bernstein and John Annesser. Bernstein and Annesser declined comment.

“Unfortunately, as our case is ongoing, we cannot offer any comment at this time,” Annesser said.

In a Feb. 21 filing in court responding to Sotis’ counsel’s request for specific documents related to Robotka’s accusation of the sale to Libya, however, Bernstein wrote “any such documents cannot be produced so as not to interfere with ongoing federal investigations.”

James Marshall, an FBI spokesman, responded that it’s “FBI policy to neither confirm nor deny the existence of an investigation.”

Robin filed a counter claim in Broward County Circuit Court, accusing Robotka of emptying the bank accounts of Kaizen and several other businesses Sotis owns, taking $102,972 on Dec. 21, one day before he filed his lawsuit against Sotis.

Sotis trained Rob Stewart, a Canadian conservationist who made underwater documentaries about sharks, on rebreathing devices many divers use on deep descents. Rebreathers circulate a diver’s air, scrubbing the carbon dioxide, which allows them to stay underwater longer. The gear also does not produce bubbles that scare fish. But the complex devices also can be more dangerous than conventional compressed-air tanks.

Stewart, 37, and Sotis were using rebreathers when they were diving in more than 220 feet of water on the Queen of Nassau wreck about 6 miles from Alligator Reef off Islamorada Jan. 31 while filming the latest installment of Stewart’s “Sharkwater” documentary series about shark conservation.

Sotis surfaced first and showed signs of breathing difficulties. Initial reports said he lost consciousness, but he denied this in a posting on the Facebook page of one of his companies, Add Helium. Crew members on the Pisces dive boat administered oxygen to Sotis. When they turned around to retrieve Stewart, he was gone. Sotis did not respond to request for comment on the incident sent to him in February and an attempt to contact him this week was not successful.

A massive three-day, 6,000-square-mile search was conducted for Stewart that included numerous assets from the U.S. Coast Guard, Navy, Customs and Border Protection, Monroe County Sheriff’s Office, Florida Fish and Wildlife Conservation Commission and the Key Largo Volunteer Fire Department’s dive team. When the official search was called off late Friday afternoon, Feb. 3, Key Largo divers, using an remotely operated underwater vehicle, found Stewart’s body 200-plus feet down on the ocean floor, about 300 feet from where he was last seen on the surface.