LAWRENCE – A Lynn man convicted last month of pulling a loaded gun on another Lynn man at an auto repair business in 2006, was found guilty Tuesday of being a felon in possession of a firearm and received 15 years in prison.Roberto Santiago, 42, who last lived at 202 Essex St., Lynn, went on trial last month and was found guilty by a Superior Court jury of possession of a firearm without a license and assault with a dangerous weapon, but innocent of possession of marijuana.However, because Santiago was also charged with being a felon in possession of a firearm, having prior convictions for drug and violent offenses, there had to be another trial to determine if the priors qualified as convictions against him.On Tuesday, Lawrence Superior Court Judge Thomas R. Murtagh, who presided over the jury trial, agreed with the commonwealth that Santiago was a felon in possession of a firearm at the time of the 2006 case during a jury-waived trial.Assistant District Attorney Michael A. Sheehan presented documentation and evidence that Santiago previously was convicted of three prior drug and violent offenses in 1990, 1992 and 1999 out of Lynn District Court.Murtagh sentenced Santiago to the minimum mandatory punishment under the law, 15 years in state prison, with no chance of early parole.Sheehan presented evidence during the first trial last month, that on the morning of Feb. 23, 2006 at about 10 a.m., Santiago pulled a .22 caliber Pardini firearm, an Italian target shooting pistol, on a worker at AK CV Joints, an auto repair business on Essex Street, who he claimed was talking too loudly with a group of other men under his second-floor window.Santiago fled following a brief encounter with the group. Police were called by the employees of the auto business.When police arrived, they arrested Santiago in his apartment and swept the radius looking for the firearm, which was found in a narrow alleyway between two buildings nearby with two magazines clips of ammunition in a box.Sheehan proposed a punishment of up to 18 years for Santiago, based on his five-page criminal record and prior convictions.