AUBURN – A judge on Monday sentenced Ryan Muncey to spend 12 years in prison in connection with the “random” stabbing death of Casey Stanley near Moulton Field last June.

Muncey, 28, of Lewiston pleaded guilty last month to manslaughter. A murder indictment against Muncey is expected to be dismissed, a court clerk said.

On Monday, Muncey turned to Stanley’s family assembled in the courtroom and apologized.

A judge in Androscoggin County Superior Court sentenced Muncey to 17 years in prison with all but 12 years suspended, plus four years of probation.

“A random act such as this must be punished decisively,” Justice Joyce Wheeler said.

Wheeler’s sentence fell midway between the two recommended sentences. A prosecutor had asked that Muncey serve 15 years; his defense attorney, eight years.

After Wheeler announced Muncey’s sentence, Stanley’s family members sitting in the front row bolted from the courtroom.

A murder conviction is punishable by 25 years to life in prison. By contrast, manslaughter is punishable by up to 30 years in prison.

The stabbing triggered a crackdown on transients drinking and partying in the area near Bonney Park.

A prosecutor said Muncey was summoned by his cousin, Paul, to Moulton Field near the Little Androscoggin River behind Florian’s Market on a June night last year.

Paul Muncey told police he had been arguing with somebody there earlier in the evening. He phoned his cousin, who was in Buckfield, to drive to the park in Auburn in case the dispute turned violent. He later phoned to say the argument had been resolved (thanks to the peacekeeping efforts of Stanley, 26, of Auburn, who was not directly involved in the argument.)

Ryan Muncey went to the scene anyway. Prosecutors said witnesses saw Stanley stagger up a hill from the river after hearing a splash. Stanley collapsed and died. Other witnesses saw a man fitting Muncey’s description leaving the scene around the same time. One of them saw a knife in his hand.

Muncey’s girlfriend, Alisha Turner, told police Muncey confessed to the stabbing, but claimed self-defense because the man he stabbed had come at him with a rock after he pushed him.

Police turned up no such rocks in the area, a prosecutor said.

The couple fled with their children to Illinois, where Muncey was taken into custody after trying to slip out a rear window.

Assistant Attorney General Leanne Zainea said Monday that the stabbing was a brutal act of random violence because Muncey decided to go to the park that night to act as “enforcer” for his cousin.

Stanley had apparently been talking on his cell phone at the time with his girlfriend who had been seeing somebody else. Muncey likely asked Stanley where his cousin, Paul, was. He likely didn’t get the answer he wanted, Zainea said.

Henry Griffin, Muncey’s attorney, outlined a differing view of events that night.

His client had gone to the scene to find his cousin. Muncey and Stanley fought, wrestling at first. Stanley threatened Muncey, who stabbed the larger man with a single thrust of his knife, Griffin said. He didn’t make a conscious decision to bring a knife. It was the one he used on the job as a sheetrocker, a job he had been doing earlier that day, Griffin said.

“There was no planning in this case,” he said. “Things got out of hand.”

Muncey, dressed in faded blue jail clothes, bowed his head as Stanley’s family testified in court. He cried when his mother, Joanne Grenier, spoke to the judge about Muncey’s life growing up without his father. “I do love my son,” she said.

Turner, his girlfriend and mother of their two children, said of Muncey: “He’s not a monster.”

Muncey said he’d go back in time “in a heartbeat” if he could. He said he cried every day in his cell about what happened that night. Turning to Stanley’s family sitting together on one side of the courtroom, Muncey stopped as he walked back to his seat and said: “I am so terribly sorry.”

Stanley’s mother, Vicky, said her son probably has forgiven Muncey for his actions. A pastor at the jail said Stanley had accepted Jesus as his savior shortly before his death.

“That says a lot,” Justice Wheeler said of Stanley’s easy ability to forgive.

Stanley’s family members urged a long sentence.

Donny Stanley Jr., Casey’s brother, told the judge: “The fact is he murdered my brother in cold blood.”

Family members lamented Stanley’s death after such a short life, before he had a chance to marry and have children. Several carried his photo.

“He has a face. He’s not just a name,” his mother said.