A man convicted of manslaughter in Australia in his wife\'s scuba-diving honeymoon drowning plotted her death for the insurance, Alabama prosecutors allege. Gabe Watson, 34, whose capital murder trial was to get under way in Birmingham Monday, allegedly killed 26-year-old Tina Thomas Watson in 2003 while they scuba-dived together ay the Great Barrier Reef, state Deputy Attorney General Don Valeska says. Gabe Watson, dubbed \"the honeymoon killer,\" allegedly hatched the murder plot in suburban Birmingham hoping to collect on his wife\'s life insurance and used the honeymoon as a pretense, essentially kidnapping her, The Birmingham News reported Valeska planned to argue. Defense attorneys contend Valeska has a vendetta against Gabe Watson, a bubble wrap salesman charged in Australia with murder in the death, but who pleaded guilty to a lesser charge of manslaughter in 2009 and served 18 months before being released from an Australian prison in November 2010. The defense lawyers argue Tina Watson\'s death was unintentional, as the Brisbane, Australia, Supreme Court allowed when Gabe Watson pleaded guilty to negligence by failing in his duties as her \"dive buddy\" by not sharing his air mouthpiece with her, the News said. He was a certified rescue diver. She was a novice diver. The defense also argues Tina Watson\'s father was the insurance beneficiary, not Gabe Watson, and Tina Watson actively planned the honeymoon, so she was not a kidnap victim, the newspaper said. A capital conviction would carry an automatic sentence of life in prison without parole. State prosecutors agreed not to seek the death penalty before Australian officials would extradite Watson. Such a deal is required under Australian extradition law. Watson, who is free on bond, remarried a woman named Kim Lewis, described by Australian media as a Tina Watson look-alike. The trial is expected to run three to four weeks.