A Rhode Island man accused of killing his wife during a 1999 scuba diving trip testified Thursday that he spent part of her inheritance on courting another woman and taking her on a cruise.

David Swain's testimony came during a heated exchange with prosecutors, who accuse him of drowning Shelley Tyre during a vacation in the British Virgin Islands so that he could pursue another woman.

Swain denies the charge, but said he vacationed with Mary Basler after Tyre's death, and that they split travel costs. He said he also took two other trips with Tyre's money.

SLIDESHOW: Rhode Island Man Accused of Murder

A forensic accountant has estimated the inheritance was worth $630,000.

"I'm sure to some degree I squandered some of the money," Swain said, denying that the inheritance afforded him a more comfortable life.

Swain at times refused to answer questions, or would only speak if he was allowed to explain his answers.

Tyre's parents alleged in a civil suit that Swain, 53, killed their daughter because he was romancing another woman and because the couple's prenuptial agreement denied him money if they divorced.

A jury found him responsible during a 2006 civil trial, and Swain was later charged with murder. He was extradited to the British Virgin Islands in 2007 and has been in jail since.

Experts have testified that they believe Swain wrestled Tyre from behind, tore off her mask and shut off her air supply.

Swain maintains his innocence and his defense lawyers said they will show the drowning of the 46-year-old was a "tragic accident."

Prosecutor Terrence Williams said Thursday that Swain's police statement and his testimony were inconsistent. He also asked Swain why he told police that he looked for his wife in shallow water when the two had split up in deep water.

"I knew at some point she would be in the reef area to look around for other things," Swain replied. "You are making false accusations."

Swain testified Wednesday that when a friend found Tyre's body, he began to perform CPR but stopped after two to three minutes because he judged she could not be resuscitated. Swain had previously worked as an emergency medical technician before opening a dive shop in Rhode Island.

Swain also denied he was seeking an intimate relationship with Basler prior to his wife's death in March 1999. He said they had emotional, not sexual chemistry.

The couple dated after Tyre's death, but Basler testified that she ended the fling in late 2000.

Swain's two children have attended the trial since it began two weeks ago, and said they have never doubted their father's innocence.

"He has been made the scapegoat for every parent's worst nightmare, to lose a child and not know why," Jennifer Bloom said.

Asked by prosecutors about what happened in 1999, Swain responded, "I would love to know the answers to put this all to rest."