SOUTH PORTLAND — A convicted sex offender living in South Portland now faces federal charges of being a felon in possession of a gun.

South Portland police and the Bureau of Alcohol Tobacco Firearms and Explosives arrested Stephen Demo, 46, this morning at his employer’s after a neighbor had spotted him with a rifle earlier this month.

Demo was convicted of two counts of gross sexual assault on a child under 14 and gross sexual misconduct, all felonies which prohibit him from possessing guns.

Police executed a search warrant at Demo’s house at 112 Romano Road this morning and seized a Remington rifle as well as a black powder rifle, which is not considered a firearm under federal law. Later, Demo directed them to a 10mm pistol hidden in a stereo cabinet.