A Briton who reported his wife missing as the newlyweds’ catamaran sunk off the Cuban coast has been arrested on suspicion of her murder after an FBI investigation.

Lewis Bennett, 41, is accused of murdering Isabella Hellmann, the mother of his baby, and intentionally sinking their vessel during the voyage from which he was rescued alone, according to documents filed in court by the bureau.

Bennett, of Poole, Dorset, was arrested on suspicion of second degree murder on Tuesday as he appeared in a Miami court where he was jailed for smuggling stolen coins during the rescue.

Lewis Bennett, a Briton whose wife mysteriously vanished as the newly-weds sailed off the Cuban coast (Broward Sheriff's Office/PA)
Lewis Bennett, a Briton whose wife mysteriously vanished as the newlyweds sailed off the Cuban coast (Broward Sheriff’s Office/PA)

He reported the 41-year-old estate agent missing in an SOS call in the early hours of May 15 saying their 37ft catamaran, Surf Into Summer, had struck an unknown object and was sinking.

FBI Special Agent James Kelley alleged in court documents that the hull appeared to have been breached in two places from inside the vessel, but this damage was not catastrophic.

Instead two underwater escape hatches had been opened which would cause the boat to flood, the agent claimed.

An associate professor at the United States Coast Guard Academy concluded the catamaran was intentionally scuttled, according to Mr Kelley’s testimony.

Bennett said during an interview that they had started their trip in St Maarten and then travelled to Puerto Rico and Cuba before starting the trip back to their home in Delray Beach, Florida.

Mr Kelley claimed that Bennett did not activate his satellite phone or register his personal locator beacon until he was in Cuba.

“Based on knowledge learned during the course of this investigation, the fact that Bennett waited until the final leg of his voyage to activate those devices is indicative of the fact that he wanted to ensure his own rescue and survival after murdering his wife and intentionally scuttling his catamaran,” the agent wrote.

Bennett has requested a presumptive death certificate for Ms Hellmann, which Mr Kelley claims is “extremely early” for a husband who “would normally want his wife to be found alive”.

The agent claims there is a monetary incentive if she is presumed dead as Bennett would inherit the American’s Delray Beach home and the contents of her bank accounts.

The FBI found that, as he was rescued, Bennett was smuggling collectable gold and silver coins that he had reported to police a year early as having been part of a haul worth 100,000 dollars (£72,000) that had been stolen from an employer’s boat in St Maarten.

Investigators searched the Delray Beach home to find a further stash of gold coins hidden in a pair of boat shoes in a closet of the master bedroom.

British-Australian dual citizen Bennett admitted a charge of transporting stolen property over the recovered coins, valued at around 38,480 dollars (£28,500), and was jailed for seven months on Tuesday.

Bennett will make his first appearance on the murder charge before a judge in Florida on Wednesday afternoon, a spokeswoman for the US Department of Justice said.