SMA LANDED ON WRONG RWY; TWR CTLRS DID NOT SEE POTENTIAL CONFLICT LESS THAN STANDARD SEPARATION ABOUT TO OCCUR.

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WHILE WORKING GND CTL I NOTICED LCL AND CABIN COORDINATOR WERE LOOKING W FROM TWR. THEY INDICATED THAT THEY COULDN'T FIND SMA X ON THE RWY 4L DOWNWIND. I POINTED ONE OUT ABEAM THE TWR. BOTH INDICATED THAT THAT WAS #2 TO FOLLOW. LCL CTLR FAILED TO ASK ON FREQ THE POS OF SMA X. WHILE THEY HAD EYES FIXED TO THE SW IN ATTEMPTS TO LOCATE THIS STEALTH SMA X; I TURNED AND SCANNED RWY 8L. WDB Y WAS IN LNDG FLARE. SUDDENLY THE WDB Y EXECUTED A MISSED APCH. AS I LOOKED DOWN THE RWY I SAW WDB Y OVERFLY THE SMA X. AS THE GEAR WAS RETRACTING; IT WAS APPROX 25-50' ABOVE THE SMA X; WHO HAD STARTED A LEFT TURN OFF THE RWY AT TXWY L. LCL CTLR TOLD SMA X TO TAXI TO PARKING AT ABF FLYING CLUB. KUDOS TO THE F/O FOR NOTICING THE SMA X ON THE RWY! IF NOT FOR HIS/HER SCANNING; WDB Y WOULD HAVE TAKEN THE SPOTLIGHT AWAY FROM RECENT ACR MLG INCIDENT. BAD NEWS; THE AREA MGR WAS GOING TO HANDLE THIS SITUATION AS AN INFORMAL INVESTIGATION. FINALLY; A PLTDEV HAS BEEN FILED; BUT IT TOOK OUR INSISTENCE TO A MGR TO DO SOMETHING! A POST SCRIPT: I HAD WORKED SMA X OUT AN HOUR EARLIER ON DEP CTL. I HAD TO TELL HIM HOW TO TURN ON HIS MODE C.