PORTLAND, Maine — Prosecutors said a Maine man from the Congo shot a former friend in an act of revenge, but the defense contended the shooting was an act of self-defense.

Daudoit Butsitsi went on trial for murder Wednesday in Cumberland County Superior Court. He is charged in the February 2010 death of 24-year-old Serge Mulongo, who was shot six times while attending a party at an apartment in Portland.

Assistant Attorney General Leane Zainea told jurors the shooting followed a number of fights, including one the morning of Mulongo’s death.

Defense lawyer Anthony Sineni said Butsitsi saw Mulongo grow more violent and unpredictable and feared for his life at the time of the shooting.