PORTLAND — A Portland woman pleaded guilty Wednesday to manslaughter for fatally stabbing her boyfriend in 2011.

As part of a plea deal, Lisa McDonald, 49, will serve four years in prison.

McDonald stabbed Carlos Ramos once in the chest at his apartment at 991 Forest Ave. on Nov. 28, 2011. He was 47 at the time of his death.

In the days following his death, neighbors described the couple’s relationship as marred by drinking and violence.

McDonald was arrested months after Ramos’s death on Feb. 22, 2012, after she was indicted on the manslaughter charge. She was sent for a mental evaluation to determine her competency to proceed with the criminal case.

McDonald had been due to stand trial later this month, with jury selection scheduled to begin Feb. 22.

But in a scheduled plea-change hearing in Cumberland County Unified Court on Wednesday, Justice Roland Cole gave McDonald a 15-year sentence with all but four years suspended. The judge also imposed a five-year probation sentence to be served after her release from prison, according to court records.

The case against McDonald was prosecuted by Assistant Attorney General Leane Zainea. McDonald’s attorney was Verne Paradie.