An additional reward is being offered for the arrest of the person responsible for the homicide of Douglas W. Cimperman. Cimperman was shot and killed during an attempted robbery on Jan. 15 while working at the ZX gas station on Carlyle Avenue in Belleville. CrimeStoppers is offering a reward of up to $5,000 and an additional $10,000 reward is being offered by Midwest Petroleum Company. The Major Case Squad of Greater St. Louis released…