LAS GND CTLR DESCRIBED INCIDENT WHEN INTRAFAC COORD WAS CONFUSED CAUSING A POTENTIAL GND CONFLICT.

Narrative

I WAS ON POS AT GND CTL W (GCW); A TRAINEE/DEVELOPMENTAL WAS RECEIVING A PROFICIENCY SKILL CHK ON LCL CTL TWO (LC2). AN HS25 WAS HOLDING SHORT OF RWY 19L AT TXWY S. A B737 WAS ON RWY 19L; A BE36 WAS ON FINAL APCH TO RWY 19R. I COORDINATED TO CROSS RWY 19L (E TO W) AFTER THE B737 DEP AND TO CROSS RWY 19R AFTER THE BONANZA ARR. UPON OBSERVING THE B737 ROLL PAST TXWY S; I INSTRUCTED THE BIZ JET TO CROSS RWY 19L AND HOLD SHORT OF RWY 19R (FOR THE BE36 ARR). THE SUPVR PERFORMING THE SKILL CHK HEARD MY INSTRUCTIONS TO THE BIZ JET; AND PROCEEDED TO TELL ME TO HOLD THE JET SHORT (OF RWY 19L). I ATTEMPTED TO STOP THE BIZ ACFT HOWEVER; THE XMISSION WAS TOO LATE. THE BIZ JET HAD PROCEEDED ACROSS THE RWY HOLD LINES. I LATER DISCOVERED THAT ANOTHER B737 WAS 'CLRED FOR TKOF' ON RWY 19L FROM INTXN L. I BELIEVE THE LC2 CTLR THEN PROCEEDED TO CANCEL THE SECOND B737 TKOF CLRNC AND INSTRUCTED THE FIRST B737 TO 'TAXI INTO POS AND HOLD.' THE BIZ JET HAD ALREADY COMPLETED XING RWY 19L PRIOR TO THE SECOND B737 HOLDING ON THE RWY.