TCASII RA TO CLB; THEN TO DSND DUE TO UNSIGHTED ACFT.

Narrative

WE WERE ASSIGNED HDG 280 DEGS BY SLC TWR FOR INITIAL CLB TO 8000 FT MSL. AFTER SWITCHING TO DEP WE WERE ASSIGNED HDG 340 DEGS CLB TO 12000 MSL. WE HEARD DEP TALKING TO ANOTHER ACFT ABOUT TCA INTRUDER WHICH WAS NOT IN RADIO CONTACT. THE OTHER ACFT ESTIMATED THE INTRUDER AT ABOUT 12500 FT MSL. WE HAD THE 727 INSIGHT BUT COULD NOT FIND THE INTRUDER ACFT. AS WE ROLLED OUT ON 340 DEG HDG AT 11700 FT MSL; WE HAD A TCASII RA CLB NOW. LOOKING AT THE TVSI I SAW 2 ACFT. ONE WAS THE 727 WHICH WE HAD IN SIGHT AND WAS WELL CLR OF. THE OTHER ACFT WAS NEVER SEEN AND THE RA WAS FLOWN TO A FEW HUNDRED FT ABOVE 12000 FT MSL WHEN THE RA TURNED TO DSND NOW. THE SECOND RA WAS FLOWN BACK DOWN TO 12000 FT MSL WHERE IT WAS RESOLVED. AT NO TIME DID WE HAVE A VISUAL ON THE INTRUDER ACFT. I FEEL THE RADAR CTLR VECTORED US INTO THE FISH BOWL PUTTING 3 ACFT IN CLOSE PROX. THIS COULD HAVE BEEN AVOIDED BY LETTING US CONTINUE W OR NW UNTIL THE NON RADIO CONTACT INTRUDER WAS WELL CLR. I FEEL DEP WAS SO EAGER TO GET A SIDE NUMBER AND ALT ON THE TCA INTRUDER ACFT OR THEY WANTED IT TO CAUSE A PROB THAT THEY WERE DETERMINED TO VECTOR ALL 3 ACFT INTO THE SMALL AIRSPACE CAUSING A PROB. THEIR FIRST AND FOREMOST DUTY SHOULD HAVE BEEN SAFETY. PREVENTING 3 ACFT IN A TCASII RA ZONE. FLY SAFE-CTL SAFE.