After pleading guilty in September, John M. Walker of Alexandria was sentenced last week to three years in prison and three years of supervised release for violating the National Firearms Act in his illegal manufacture, ownership and sale of fully automatic machine guns, federal law enforcement officials announced last Friday.

Walker, whose Utica Avenue home was raided by officials who seized 75 guns in June after a three-month long federal investigation, admitted to converting two semi-automatic Uzi firearms into fully automatic Uzi machine guns and removing the serial numbers on the weapons before selling them to an undercover federal agent for roughly $2,000 each, according to court documents.

The two transactions took place in May at the Safeway grocery store on South Van Dorn Street and the other in June at the Fuddruckers restaurant on Duke Street, not far from Walker’s home, according to an affidavit.

The 50-year-old also agreed to forfeit 19 firearms that he had illegally converted into machine guns, having failed to register them with the National Firearms Act Registration and Transfer Record and failed to pay the required taxes to manufacture, transfer or possess firearms in accordance with the National Firearms Act, court records stated.