(MT. VERNON, IL) – A Mt. Vernon teen arrested Saturday in the fatal shooting of 20 year old Carlos Johnson was formally charged Monday with three counts of first degree murder.  The charges allege 18 year old Roderick S. Oats, Jr. shot Johnson with a firearm without lawful justification, with knowledge the act would cause his death, with knowledge the act created a strong probability of death, and with the intent to kill. Oats faces a potential sentence of between 20 years to life for the crime. Oats was arrested by Benton police late Saturday night in connection with the shooting death of Johnson earlier in the day in the 700 block of South 25^th Street in Mt. Vernon. According to Mt. Vernon police, Oats was arrested at 11:39 p.m. without incident. MVPD learned of Oats’ possible location during the investigation and requested Benton police locate and arrest him. The shooting took place around 4:30 p.m. Saturday in the 700 block of South 25^th Street. Officers responded to a call about shots fired. Shortly after they arrived they received a call from Good Samaritan Hospital reporting a person was in the emergency room with gunshot wounds. That person, later identified as Johnson, has died from his injuries. Oats is in the Jefferson County Justice Center after his initial court hearing Monday. He is currently awaiting trial in Marion County on weapons charges. Oats was arrested in January after the vehicle he was in was reportedly seen leaving a party in Salem where a double shooting had just occurred. A Salem man has since been convicted for those shootings. Reports indicate Oats was stopped in the Denny’s parking lot in Salem and he allegedly admitted to police that he had a gun in his pants pocket. The .38 caliber weapon was reportedly loaded with four bullets and the hammer was cocked. Deputies initially arrested Oats for alleged unlawful use of a weapon but further investigation revealed that in 1982 the gun had been stolen in Massachusetts. That resulted in an additional charge against Oats of possessing a stolen firearm.