KEENE – The Swanzey man accused of stabbing a Marlborough teenager to death last summer is expected to plead guilty in court Wednesday afternoon.

Ethan A. Wilson, 20, faces charges of first-degree murder and second-degree murder for the July 24, 2011, death of 17-year-old Craig Metivier of Marlborough.

According to a negotiated plea on file at the Cheshire County House of Corrections in Keene, Wilson is expected to plead guilty to second-degree murder. He would serve 25 to 50 years in the N.H. State Prison in Concord, according to the agreement.

If available, he would be expected to attend anger-management classes and the victim impact program in prison, make restitution to the N.H. Victim Assistance Fund, and waive a sentence review.

Also according to the yet-to-be-accepted plea, Wilson can have two and a half years taken off his minimum sentence suspended for 10 years upon release if he completes the anger-management program and the victim impact program and obtains an associate’s degree.

The first-degree charge alleges Wilson purposely caused the death of Metivier by stabbing him in the heart and lung. The second-degree charge alleges Wilson recklessly caused Metivier’s death “under circumstances manifesting an extreme indifference to the value of human life, by stabbing Craig Metivier multiple times with a knife.”

Wilson is currently incarcerated in the Cheshire County House of Corrections.

Police responded to a disturbance on Dunbar Street in downtown Keene on the night of July 24. Metivier was found stabbed and was taken to Cheshire Medical Center, where he died.

The next morning Wilson was arrested and charged with the death. Metivier died of a stab wound that perforated his left heart and lung, according to the state medical examiner, who ruled the death a homicide.

According to the arrest affidavit, Wilson confessed when he was interviewed by police and a state trooper on July 25.

In the interview, he said Metivier was “just hitting him in the head.”

“He stated that when he looked up, he saw Metivier reach into his pocket and he did not know what Metivier was going to do, so he pulled out his knife that was clipped to his waistband and stabbed Metivier,” the affidavit said. “After Metivier was stabbed, Metivier continued to come after him and told Wilson that he was going to kill him. The defendant did not want to get punched, so he stabbed Metivier again. The defendant started to run off after he stabbed Metivier again, and when he looked back, he saw Metivier hit the ground, so he ran away faster.”

Wilson said in the interview the fight occurred because Metivier and another person “had ripped him off.”

In the arrest affidavit, Wilson does not say how Metivier had “ripped him off” but said the other person had stolen a smoking pipe and money from him and kept $100 Wilson had asked him to use to buy cocaine.