AUGUSTA – A Portland police officer was justified when he fatally shot a 26-year-old man during an altercation last summer that broke out as police investigated suspected drug activity, state Attorney General Steven Rowe said Thursday.

Portland police Sgt. Robert Martin believed his life was being threatened when he shot Richard “Cali” Duncan of Portland during the late-night incident Aug. 25, Rowe said.

Based on an investigation by his department, Rowe said he also determined that Martin “reasonably believed that deadly force on his part was necessary to protect himself and others in countering the imminent threat against them.”

The shooting took place during an altercation that broke out as officers were investigating suspected drug activity involving two carloads of suspects near the intersection of Pleasant and Forest Avenues in Portland.

Martin led a second group of police officers who were called to the scene. As police began making arrests, they learned that Duncan was carrying a gun or had one in the car.

Duncan became physically combative when the officers tried to remove him from the car and kicked one of the officers. Martin ordered Duncan’s arrest, and while officers tried to handcuff him they saw he was holding a semiautomatic pistol.

As Martin tried to wrestle the gun away from Duncan to prevent him from firing, the two men fell to the ground, according to Rowe.

Still unable to disarm the suspect or stop him from fighting, Martin held his service weapon to Duncan’s lower back and discharged it.

“Recovered by the officers immediately thereafter was the firearm that had been in Duncan’s hand, a .25-caliber semiautomatic pistol,” Rowe said.

Duncan was treated at the scene by emergency medical personnel and taken to Maine Medical Center in Portland, where he died.

State law says a police officer may use deadly force if the officer believes he or a third person is threatened by unlawful deadly force, and must use deadly force to counter that threat.