SAN DIEGO (CNS) - A Los Angeles County man Thursday pleaded guilty to second-degree murder for beating and strangling his wife on a cruise ship two years ago as the vessel returned to San Diego from a five-day trip to Cabo San Lucas.

Robert John McGill, from Winnetka in the San Fernando Valley, faces life in prison when he is sentenced Nov. 8 by U.S. District Judge Irma Gonzalez.

In a probable cause statement filed with a criminal complaint, an FBI special agent said McGill "stated he killed his wife (Shirley) in the bathroom of their cabin with his bare hands."

Crew members on the 2,052-passenger ship Carnival Elation responded to a domestic dispute shortly before 8:30 p.m. on July 14, 2009 -- the defendant's 55th birthday -- in the couple's cabin and found the victim's body.

The FBI -- which investigated because the murder occurred in international waters -- said Shirley McGill, who was also 55, was killed when the ship was about three hours out of Cabo San Lucas. She'd been dead for about two hours when her body was discovered.

McGill's attorney said in court papers that his client was extremely intoxicated aboard the ship, and witnesses described the defendant as stumbling around and barely able to walk.

The McGills, married in 2003, were former high school sweethearts who got back together later in life.

Robert McGill, now 57, worked for 30 years with the Los Angeles County Office of Education teaching at-risk teenagers.