NMAC BTWN A PIPER PA28 ON 2 MI R BASE AT CGI; AND A CESSNA ON A L BASE XING 400 FT OVER THE TOP OF THE PIPER. TWR CTLR HAD DIFFICULTY LEARNING THE EXACT LOCATION OF THE CESSNA SINCE IT WAS NOT IN SIGHT.

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ON AUG/XA/02; I WAS ENRTE TO CGI ARPT ON A VFR FLT PLAN UNDER VMC; SCATTERED CLOUDS AT 6000 FT MSL; VISIBILITY GREATER THAN 6 MI; WINDS 040 DEGS AT 6 KTS; NO OTHER SIGNIFICANT WX. AT 20 NM OUT; I BEGAN MONITORING THE TWR FREQ. 3 OTHER ACFT WERE INBOUND FROM THE NW AND NE. AT 10 NM; APPROX XA00Z; I MADE MY INITIAL CALL TO THE TWR AND WAS INSTRUCTED TO RPT A 5 MI R BASE FOR RWY 10. SHORTLY PRIOR TO MY CALL; THE CTLR INSTRUCTED A CESSNA; UNKNOWN TYPE; APCHING FROM THE N; TO CALL A 2 MI L BASE FOR THE SAME RWY. AT APPROX 4 MI OUT; THE CESSNA INFORMED THE TWR HE WAS EXECUTING A 360 DEG TURN TO 'LOSE SOME ALT.' THE CTLR RESPONDED BY ASKING THE CESSNA HIS CURRENT POS BECAUSE HE HAD A CHEROKEE COMING IN FROM THE S; MY ACFT. ALTHOUGH NO TFC WARNING WAS ISSUED; I INFORMED THE CTLR I DID NOT HAVE THE ACFT IN SIGHT AND WAS NOW ON A 5 MI R BASE AT 1200 FT. I WAS INSTRUCTED TO RPT A 2 MI BASE. AFTER NO RESPONSE FROM THE CESSNA; THE CTLR INFORMED THE CESSNA HE WAS NOT IN SIGHT. AFTER SEVERAL SECONDS; THE CESSNA PLT STATED HE WAS 2 MI FROM THE APCH END OF RWY 10. AT THIS POINT; I WAS ON A 2.4 MI R BASE. THE CESSNA THEN PASSED DIRECTLY OVERHEAD GOING IN THE OPPOSITE DIRECTION AT APPROX 1500 FT. I INFORMED THE CTLR THAT THE CESSNA WAS DIRECTLY OVERHEAD; OPPOSITE DIRECTION; AND WAS NOW NO FACTOR. I WAS THEN CLRED TO LAND. IN MY ASSESSMENT; THE CTLR FAILED TO OBTAIN ADEQUATE INFO FROM INBOUND ACFT (DISTANCE/BEARING FROM ARPT WITH VOR ON FIELD; ALT; SPD); PROVIDE ADEQUATE SPACING OF ACFT; NOR DID HE PROVIDE ADEQUATE TFC WARNINGS. I WILL ALSO NOTE THAT DURING OUR DEP AFTER LUNCH THE SAME CTLR BECAME CONFUSED; WHICH HE ACTUALLY STATED TO THE PLT; AS TO THE LOCATION OF ACFT INBOUND TO CGI.