According to a press release from the Alaska Department of Corrections, 43-year-old Kenneth Mazanares was found unresponsive in his cell at Lemon Creek Correctional Center on the morning of July 14.
Prison officers and medical staff performed life-saving measures, but he was pronounced dead shortly after emergency responders arrived at the scene.
Foul play is not suspect, the release said.
According to a news release from the US Department of Justice, the couple from Santa Clara, Utah, argued the night of July 24, 2017, while on the cruise with their daughters and extended family members.
She said she wanted a divorce and told her husband to disembark the vessel at Juneau and go home to Utah, the news release said. Kenneth Manzanares told the two daughters to leave the room, and they went into the adjoining room with relatives, the news release said.
After hearing screams from the room, the girls went to a connected balcony and saw their father straddling their mother on the bed striking her on the head with his fists, according to the release.
Security and medical personnel arrived and tried to save Kristy Manzanares, but were unsuccessful. The release said Kristy Manzanares died of blunt force trauma to her face and head.
The case fell under federal jurisdiction because the killing occurred while the ship was in US waters. Manzanares has been in custody since his arrest.
CNN’s Steve Almasy contributed to this report.