A BA32 FO RPTED A CONFLICT WITH A CITATION IN THE VICINITY OF RDU.

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WE WERE ON AN ASSIGNED HDG OF 080 DEGS LEVEL AT 8000 FT; BEING RADAR VECTORED FOR LNDG AT RDU. THE LNDG RWY FOR THIS APCH WAS RWY 23R WHICH WAS ASSIGNED BY ATC. THE CAPT WAS THE PF. THE FO WAS THE PNF. WE RECEIVED A TCASII ALERT THAT TFC WAS APCHING AT A VERY HIGH RATE OF SPD. THE TCASII IMMEDIATELY BEGAN TO INFORM US THAT THERE WAS A 'TFC; TFC' THREAT. I IMMEDIATELY INTERPED THE INFO FROM THE TCASII SCREEN AND BEGAN TO FOCUS OUTSIDE THE COCKPIT FOR AN IMMEDIATE VISUAL AT THE 2-3 O'CLOCK POS. WITHIN 2-3 SECONDS OF THE TCASII INSTRUCTING US TO 'CLB; CLB;' I OBTAINED A VISUAL ON THE JET AND TOLD HIM (THE CAPT) TO CLB QUICKLY. ATC ADVISED US AFTER CLBING TO ABOVE 8000 FT (BY +400-600 FT TO CLR THE CONFLICT) THAT THE JET TFC WAS AT FAULT AND WE WERE NOT AT FAULT. WE DEVIATED FROM ALT TO PREVENT A POSSIBLE MIDAIR COLLISION. THE TCASII WAS VERY EFFECTIVE IN AIDING OUR DECISION TO CLB. THE CITATION JET OBVIOUSLY DID NOT HAVE CTL OF THEIR ACFT WHEN THE CTLR RELAYED TO THEM THAT THEY HAD DEVIATED FROM THEIR ASSIGNED ALT BY AT LEAST 1000 FT. CORRECTIVE ACTIONS HERE ARE THAT THERE SHOULD HAVE BEEN SITUATIONAL AWARENESS AND CRM APPLICATIONS IN PLACE ON BEHALF OF THE CITATION CREW. I THINK THIS WILL ENHANCE THE SAFETY LEVEL AND MAKE FLYING MUCH SAFER.