Timothy Adarna this morning admitted to murdering his stepfather, Robert Ramos, in Ewa Beach two years ago and faces at least 20 years in prison for the crime.

A Circuit Court jury last summer couldn't reach a verdict in the case, voting 10-2 that Adarna, 21, was guilty of manslaughter, not murder, because he was under "extreme emotional disturbance" when the crime was committed.

The jury convicted Adarna of first-degree arson for setting fire to the residence where Ramos was killed.

In a plea deal with prosecutors, Adarna agreed to plead guilty to murder in return for a recommendation that he serve 20 years behind bars, the maximum penalty for manslaughter. The murder charge carries a life sentence with the possibility of parole.

Circuit Judge Michael Town accepted the agreement and set sentencing in March.

The Hawaii Paroling Authority will determine how much time Adarna will serve before being considered for parole.

Deputy Prosecutor Kevin Takata said, "We still believe this is a murder case," but called the plea agreement "a fair and amicable result" based on the earlier 10-2 jury vote for manslaughter.

Robert Ramos, the victim, was "loved by all," said Takata.

Adarna, a Campbell High School graduate and military veteran, has said he doesn't remember what happened.

Defense lawyer David Hayakawa called it "a mystifying case" that will apparently never be adequately explained.

"I don't think we'll ever really know what happened," Hayakawa said.

Both Takata and Hayakawa expressed confidence that the Hawaii Paroling Authority will abide by the 20-year incarceration recommendation.

Takata said that in 2007, the average minimum penalty set by the HPA in second degree murder cases was 56 years in prison.

Adarna could have chosen to go to trial again on the murder charge, Takata said, but noted that his office could have hired an expert to dispute the "extreme emotional disturbance" defense.

Adarna was 19 when he was arrested for killing Ramos, whose body was found in a burned-out bedroom of his house.

Neighbors told police they heard Ramos arguing with a man and saw someone who looked like Adarna leave the house shortly before a fire was noticed. An autopsy determined Ramos, 55, bled to death after being stabbed in the neck and hit on the head and chest with a blunt object.