OAKLAND — Police are investigating how Gregory Hammerbeck, a 41-year-old felon living with several roommates in a house on Old Belgrade Avenue, got a handgun they say he used to threaten another person in the household.

Friday night, officers with the Oakland Police Department arrested Hammerbeck and said they found a 9-mm semi-automatic gun in a locked upstairs bedroom, according to Capt. Rick Stubbert, who participated in the arrest.

Stubbert said police got a search warrant and went to the home around 8:45 p.m. after they were told earlier in the day that Hammerbeck had used the handgun to threaten someone in the residence. Police were initially told by members of the household that Hammerbeck was not there. Stubbert and the three other officers eventually found Hammerbeck in the house and arrested him without incident, Stubbert said.

Police say Hammerbeck threatened the man who lived at the home about a week before the arrest. The man who says he was threatened, who was not physically injured, didn’t report the threats until Friday “because there was some fear involved,” Stubbert said.

The alleged victim has moved out of the house, which overlooks Lakeview Cemetery and Messalonskee Lake.

Stubbert would not release further details, citing an ongoing investigation. “It involved him, a firearm, and somebody being threatened,” he said.

Hammerbeck has been charged with criminal threatening with a dangerous weapon and possession of a firearm by felon, both class C felonies that each carry a maximum penalty of five years in prison and a $5,000 fine, according to the state attorney general’s office.

This is the third time Hammerbeck has been arrested in Oakland in the past year.

In March, Hammerbeck was arrested at the same residence on a warrant from Kennebec County District Court for unpaid fines and fees. In April, he was arrested on a charge of violation of a protective order.

Hammerbeck was released on $4,000 unsecured bail and is scheduled to appear in Kennebec County Superior Court on Feb. 25.

Matt Hongoltz-Hetling — 861-9287 [email protected] Twitter: @hh_matt