SANTA ANA – A Fountain Valley man accused of shooting his fiancee to death pleaded guilty Friday to manslaughter and was sentenced to 16 years in prison.

In exchange for Philip Ngoc Nguyen’s guilty plea, prosecutors dropped a felony murder charge that the 29-year-old had faced in the slaying of Uyennie Ton, court records show.

The shooting occurred on Feb. 25, 2011 at the Fountain Valley trailer Nguyen shared with his parents. Nguyen had been in a relationship with Ton for around three years, and he had proposed to her a few days before the shooting.

Authorities say Ton had been angered to discover that Nguyen was having a sexual relationship with another woman. However, prosecutors said, Ton agreed to Nguyen’s marriage proposal after he promised to end the other relationship.

The night of the shooting, prosecutors allege, Nguyen called the other woman, unsuccessfully trying to get her to come over to his home for sex. After the call, Nguyen and Ton got into an argument, prosecutors said, which ended with Nguyen shooting Ton in the head.

The Orange County Grand Jury indicted Nguyen on a felony murder charge, as well as potential sentencing enhancements for personal use of a firearm causing death. Had he been convicted of the original charge, Nguyen could have faced up to 50 years to life behind bars.

Contact the writer: semery@ocregister.com