A Florida man whose newlywed wife went missing at sea as the couple sailed off the Bahamas has pleaded guilty to a manslaughter charge in federal court.

Lewis Bennett entered the plea at a hearing Monday in Miami. The 41-year-old faces a maximum eight-year prison sentence in the May 2017 disappearance of Isabella Hellmann, his wife of three months.

Bennett is a mining engineer with dual British and Australian citizenship. He had insisted he left Hellman on deck when he went to their cabin to go to sleep. Bennett said he awoke when the boat hit something and Hellman was gone.

The FBI says an inspection of the catamaran showed portholes below the waterline had been opened and damage to the twin hulls appeared to have been caused from the inside.