Prosecutors say Gabe Watson planned to kills his wife, Tina Watson, 26, even before the trip while the two were still in Alabama. This gives the state jurisdiction over Tina Watson's death.
Watson's attorney claims that his client had only taken a brief rescue certification course two years before the couple's honeymoon trip along the Great Barrier Reef in 2003.
"It was a half-day class," attorney Joseph Basgier told CBS's "Early Show." "He had never participated in a rescue dive before. He wasn't an expert rescuer. He had never done it, and he was scared, too. This was his new wife."
Tina Watson's family members said before she died, Gabe Watson wanted her to increase the value of her life insurance policy and name her husband as the beneficiary.
However, an attorney for Watson said the $33,000 insurance payment was made to Tina Watson's father - not her husband.
Watson, 33, pleaded guilty to manslaughter. He arrived in Los Angeles on Thursday after he was deported from Melbourne, Australia.
The Associated Press contributed to this story.