DVT CTLR EXPERIENCED NMAC WITH 2 ACFT IN THE PATTERN.

Narrative

I WAS WORKING THE LCL CTL S POS AT DVT. I HAD A SYMPHONY ON DOWNWIND WITH A BONANZA ENTERING DOWNWIND TO FOLLOW THE SYMPHONY. I EXTENDED THE SYMPHONY ON DOWNWIND TO ALLOW ROOM FOR 2 DEPS. I THEN ASKED THE SYMPHONY TO TURN BASE. AT THIS TIME; AN ARCHER FROM A FLT SCHOOL CALLED OFF SCOTTSDALE INBOUND. THE ARCHER WAS TOLD TO RPT 1 MI E OF CAVE CREEK ROAD (A 4 MI FINAL RWY 25L). AT THIS TIME THE SYMPHONY WAS ON FINAL WITH THE BONANZA TURNING FINAL. SHORTLY THEREAFTER; THE ARCHER RPTED AND WAS SEQUENCED TO FOLLOW THE BONANZA AND ASKED IF HE HAD THE BONANZA IN SIGHT. THE ARCHER STATED HE HAD PASSED THE BONANZA. THE BONANZA STATED 'THAT WAS CLOSE.' I INSTRUCTED THE ARCHER TO MAKE A L 360 DEG TURN; ROLL OUT ON FINAL TO FOLLOW THE BONANZA. I THEN TOLD THE BONANZA THE ARCHER WAS INBOUND FROM SCOTTSDALE AND WAS EVIDENTLY CLOSER THAN HIS RPT. THE BONANZA PLT STATED THAT SIT WOULD 'MAKE HIM NO LESS DEAD.' I ENCOURAGED THE PLT TO CALL THE FACILITY. HE STATED IT NEVER HELPS. WE THEN LANDED AND THE GND CTLR DISCUSSED THE IMPORTANCE OF NOT MAKING COMMENTS ON FREQ AND TO CALL THE FACILITY. HE STATED HE WOULD NOT CALL. HE LATER FILED AN NMAC. FACTORS: THE IMPORTANCE OF REALISTIC RPTING POINTS. AT THE POINT THE ARCHER RPTED A 4 MI FINAL HE HAD ALREADY PASSED THE BONANZA. THIS WOULD HAVE MEANT THE BONANZA TURNED BASE TO FINAL FURTHER THAN THAT THE BONANZA WAS IN THE PATTERN -- THAT WAS NOT THE CASE. THE ARCHER WAS CLOSER -- A COUPLE OF MI IN A VFR TWR IS A LOT OF SPACE AND IMPORTANT TO LCL CTLRS.