BANGOR, Maine — Two of the four men involved in the St. Patrick’s Day 2012 beating of a man with a baseball bat in a parking lot across the street from Pat’s Pizza in Orono pleaded guilty to assault charges Tuesday at the Penobscot Judicial Center.

Christopher Duffey, 24, of Scituate, Mass., and John Joyce, 24, of Portland pleaded guilty to Class D assault.

In a plea agreement with prosecutors, Duffey was sentenced to 30 days in jail and Joyce was sentenced to 21 days.

Nappi Giovanni, 23, of Portland pleaded guilty to the same charge on June 12 and began serving his 30-day sentence five days later, Alice Clifford, assistant district attorney for Penobscot County, said Tuesday after the courthouse closed for the day.

In addition to jail time, Superior Court Justice Kevin Cuddy ordered the three defendants to pay a total of $3,580 in restitution to the victim.

The fourth defendant, James O’Lore, 24, of Portland, who was not charged in connection with the assault, is scheduled to plead guilty to one count of criminal mischief, a Class D crime on Thursday, Clifford said. There is not yet a plea agreement in that case.

The four men all graduated from the University of Maine, according to information given to Cuddy on Tuesday. They were in downtown Orono on March 17, 2012, to celebrate St. Patrick’s Day.

As the quartet were leaving a bar, they exchanged words with the male victim and a woman, Clifford told Cuddy. An argument ensued in the parking lot and the victim took a baseball bat out of his car because he felt threatened.

The fight became physical and the bat was taken away from the victim, the prosecutor said. The victim suffered a concussion, a broken vertebrae and fractured cheekbone in the fight but was not hospitalized overnight.

O’Lore is accused of hitting the victim’s car with the bat, Clifford said.

“This is absolutely inappropriate behavior for University of Maine graduates,” Cuddy told Duffey and Joyce in imposing their sentences. “There is no license for this kind of behavior just because it is St. Patrick’s Day.”

Duffey told Cuddy that the experience of being arrested and facing charges had been “a life changing experience for me.” He said that he had quit drinking and repaid his mother the money she loaned him to pay his lawyer.

Cuddy ordered Joyce to begin serving his sentence July 23 and Duffey to begin serving his on Aug. 30.

The penalty for a Class D crime is up to a year in prison and a fine of up to $2,000.