ic ide : ▁Life ▁on ▁the ▁Street ▁In ▁ 1 9 9 3 , ▁Johnson ▁became ▁part ▁of ▁the ▁original ▁cast ▁of ▁the ▁television ▁series ▁Hom ic ide : ▁Life ▁on ▁the ▁Street ▁playing ▁Det ect ive ▁M eld rick ▁Lewis ▁for ▁all ▁seven ▁seasons ▁and ▁the ▁re union ▁movie , ▁as ▁well ▁as ▁direct ing ▁several ▁episodes . ▁Johnson ▁regularly ▁impro vised ▁during ▁film ing ▁and ▁made ▁up ▁his ▁own ▁j okes ▁and ▁dialog ue ; ▁writer ▁and ▁producer ▁James ▁Y osh im ura ▁called ▁Clark ▁the ▁" king ▁of ▁the ▁ad ▁lib ". ▁Although ▁the ▁ensemble ▁nature ▁of ▁the ▁show ▁meant ▁that ▁Johnson ▁never ▁played ▁a ▁minor ▁role , ▁he ▁became ▁an ▁even ▁larger ▁presence ▁after ▁his ▁character ▁was ▁pa ired ▁with ▁a ▁new ▁partner , ▁Mike ▁K ell erman ▁( play ed ▁by ▁Re ed ▁Diam ond ). ▁The ▁two ▁detect ives ▁became ▁the ▁central ▁figures ▁in ▁a ▁plot ▁line ▁surrounding ▁a ▁Baltimore ▁drug ▁lord ▁whose ▁financial ▁resources ▁and ▁front ▁as ▁a ▁devoted ▁community ▁servant ▁make ▁it ▁nearly ▁impossible ▁for ▁the ▁police ▁department ▁to ▁charge ▁him . ▁Johnson ▁made ▁the ▁transition ▁to ▁director ▁with ▁the ▁season ▁four ▁episode ▁" Map ▁of ▁the ▁Heart ". ▁He ▁also ▁directed ▁" B et ray al ", ▁" Val ent ine ' s ▁Day ", ▁" Full ▁Court ▁Press " ▁and ▁" The ▁Tw enty ▁Per cent ▁Solution ". ▁David ▁Simon , ▁the ▁author ▁of ▁the ▁non - f iction ▁book ▁Hom ic ide ▁was ▁based ▁upon , ▁as ▁well ▁as ▁a ▁writer ▁and