Lewis said his wife was the victim of a boating accident. Today, he's been jailed over her death.

From the moment US coast guards found Lewis Bennett floating alone in a life raft near the Bahamas two years ago, the former Gold Coast businessman maintained that his wife had been killed in a tragic boating accident.

But prosecutors claimed otherwise, and on Tuesday, local time, a Miami court sentenced him to eight years behind bars.

The dual British/Australian citizen accepted a plea deal in November that saw him convicted of a reduced charge of involuntary manslaughter over the death of his wife Isabella Hellmann, who vanished when their luxury 37-foot catamaran sunk in May 2017.

The Colombian-born woman’s body has never been found.

The mysterious collision and the stolen coins.

Bennett and Hellmann, a real estate broker, had been married for three months and were returning home to Florida from their belated Caribbean honeymoon when Bennett made an SOS call to say his boat was sinking.

Bennett told authorities that he was sleeping below deck when he was jolted awake by what felt like a collision with an unknown object. Bennett said he scrambled topside and jumped on a lifeboat, but his wife – who had agreed to take watch – was nowhere to be seen.

In a statement released after Tuesday’s sentencing, the U.S. Attorney’s Office noted that “Bennett did not require Ms. Hellman to wear a life jacket, harness, or personal locator beacon while at the helm during this night watch,” nor did he set off emergency flares or use the attached dinghy to search for her when he woke.

“It was not until Bennett boarded the life raft that he called for help and reported his wife missing, approximately 45 minutes after he was awakened,” the statement read.

In the lifeboat with Bennett was a bag filled with roughly US$40,000 (AUD$55,500) worth of gold and silver coins; coins that prosecutors later proved he had stolen from his boss while working as a crewman on a yacht in 2016.

Bennett was convicted of the theft and was serving seven months in a Miami prison.

But in February 2018, prosecutors added a more serious crime to his rap sheet, when they charged him second-degree murder.

'You're pushing me away': text messages point to marital strife.

During the court process, evidence was presented that suggested the vessel had been "intentionally scuttled", rather than involved in a collision. Investigators had discovered that the catamaran had sustained seemingly deliberate damage from the inside, and that escape hatches below the waterline had been opened, causing the cabin to flood.

Prosecutors alleged that Bennett had killed his wife and staged the accident in order to free himself of "marital strife". They alleged that the pair had been arguing about finances and where to raise their daughter, Emelia, who now lives with Bennett's relatives in the UK and is due to turn three in July.

Court documents revealed Bennett and Hellmann owed property taxes and also faced having their condo’s electricity cut off, and also catalogued tense text messages between the pair.

"This morning I was afraid to get home with the coffee but I walked in and I was right,” one text message from Hellmann read, according to The Times. “I found an angry person, this is very sad.”

“Sometimes I can be a pain in the a** and more but you need to change your attitude… you make me crazy shouting, yelling, swearing… YOU ARE PUSHING ME AWAY,” read another.

According to The Ledger, shortly after the honeymoon tragedy, Bennett filed a motion with the Florida courts asking that his wife be declared dead; a move that would have given him possession of their condominium and other items that belonged to her. A judge rejected the motion.

Despite the prosecution's evidence, the murder charges were dropped in exchange for his guilty manslaughter plea. As part of the deal, Bennett also renounced all claims to Hellmann's estate.

Bennett jailed.

Prior to his sentencing on Tuesday, Bennett expressed his “sincerest regret for their pain” to Hellmann’s family and asked Judge Federico Moreno “to permit me to be with my daughter as soon as possible so I can raise her to my wife’s wishes.”

In delivering the sentence — the maximum for involuntary manslaughter — Judge Moreno offered his sympathy to the Hellmanns but said he “can only sentence for what the defendant has admitted,” The Ledger reported.

An attorney for the family told the newspaper that they were satisfied with the result. “This concludes a sad chapter for this family,” the attorney said. “All we can do is hope these visits go forward so Emelia grows up knowing she has two families. She’s lost her mother, but not her mother’s family.”