MIL C130 HAD NMAC WITH SMA X IN CLASS D AIRSPACE. SEE AND AVOID CONCEPT.

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I WAS WORKING THE LCL CTL POS IN A VFR TWR. SMA X HAD DEPARTED VFR EBOUND OFF OF RWY 24L. X WAS TOLD TO MAKE A R TURN EBOUND. ANOTHER CESSNA; Y CALLED ON FREQ 10 MI E INBOUND ABOUT 3 MIN LATER; TFC WAS ISSUED BTWN X AND Y. WE WERE EXPECTING A C130 IN THAT MORNING AND CITY OPS HAD CALLED ASKING IF WE KNEW WHERE HE WAS. I CALLED THE APCH CTL AND ASKED THEM IF THEY HAD ANYTHING LIKE THAT INBOUND. APCH SAID THEY WERE JUST ABOUT TO CALL ME WITH THAT INBOUND; AND THAT HE IS 5 MI SE. X THEN RPTED AT 2500 FT REQUESTING A FREQ CHANGE; WHICH WAS APPROVED. THE C130 THEN CALLED ON FREQ AND WAS TOLD TO RPT A 2 MI L BASE FOR RWY 24R. I THEN ISSUED TFC TO Y INBOUND FROM THE E WHO APPEARED TO BE ON A DOGLEG TO BASE ENTRY FOR RWY 24L. Y SAID HE HAD THE C130 IN SIGHT. APCH THEN CALLS OVER AND SAYS THAT THE C130 HAS TFC AHEAD AT 2500 FT. I THEN CLRED THE C130 TO LAND ON RWY 24R. DURING HIS ACKNOWLEDGEMENT; HE RPTED THAT A CESSNA HAD JUST PASSED HIM L TO R ABOUT 100 FT ABOVE. THE C130 WAS 2 MI S OF THE ARPT ON A L BASE DSNDING RAPIDLY OUT OF 3500 FT WHEN THIS OCCURRED. THE ACFT WAS LATER IDENTED AS X BY THE C130 PLT. SEVERAL ASSUMPTIONS LED TO THIS OCCURRENCE. 1) THE INCIDENT OCCURRED 7 MIN AFTER X DEPARTED THE ARPT. EXPERIENCE; AS WELL AS TIMING SEVERAL OTHER ACFT; INDICATE THAT DEPARTING RWY 24L WITH A R TURN NE; E; OR SE REQUIRES 5 MIN TO CLR CLASS D AIRSPACE AND BE AT LEAST 5 MI AWAY; SINCE 6-7 MIN HAD ELAPSED WHEN X REQUESTED A FREQ CHANGE; I BELIEVED HIM TO BE CLR OF THE AIRSPACE. 2) BOTH THE C130 AND THE INBOUND CESSNA Y WERE IN SIGHT; AS THE C130 ENTERED L BASE. THE CESSNA WAS IN CLOSE PROX ON DOG LEG TO BASE BEHIND THE C130. WHEN TFC WAS PASSED FROM APCH; I BELIEVED IT TO BE IN REF TO THE INBOUND CESSNA IN CLOSE PROX TO THE C130; WHOM I HAD IN SIGHT AND WHO HAD PREVIOUSLY RPTED HAVING THE C130 IN SIGHT. 3) ANTICIPATING; BELIEVING ; AND ASSUMING ARE ALMOST THE SAME THING.