NMAC BTWN THE RPTING SAAB SF340 IN CRUISE AT 4000 FT; JUST HANDED OFF TO SUBSEQUENT APCH CTL; AND A C210 GIVEN A VFR DSCNT THROUGH THE SF340 FLT PATH. TCASII RA CAUSED SF340 FLC TO SEE AND TAKE EVASIVE ACTION TO AVOID THE C210. THE C210 PLT DID HAVE THE SF340 IN SIGHT; BUT THE CTLR WAS UNABLE TO COM WITH THE SF340 OR THE PREVIOUS CTLR OF THE SF340 TO PROVIDE A TA.

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AT THE HDOF FROM DTW APCH TO FNT APCH; WE RECEIVED AND COMPLIED WITH AN RA. WE WERE ON A 360 DEG HDG AT 4000 FT WITH THE AUTOPLT ENGAGED AND THE FO FLYING. THE RA ANNUNCIATED WITH NO TA EXACTLY AT THE TIME OF CHK-IN WITH FNT APCH. NO REF OF THE TFC WAS GIVEN BY DETROIT ATC. TFC WAS 12 O'CLOCK POS; 5 MI; 400 FT ABOVE AND DSNDING. THE FO COMPLIED WITH THE 'CLB; CLB NOW' WHILE I CONTACTED FNT APCH TO INFORM THEM OF OUR DEV. FNT APCH SAID THAT THEY WERE TALKING TO AND CLRED THE CENTURION THROUGH OUR ALT REF TO US AND THEN ISSUED US A 320 DEG HDG. WITH THE SHORT RANGE; WE WERE ONLY ABLE TO CLB TO 4300 FT MSL AND COMMENCE THE L TURN BEFORE THE TFC PASSED 300 FT TO OUR R AND 200 FT BELOW US. ESSENTIALLY; THE POS WE HAD JUST VACATED. AFTER LNDG AT FNT; OUR DEST; I CALLED FNT APCH VIA THE TELEPHONE. I TALKED TO CIC; WHO SAID THE RADAR CTLR ATTEMPTED TO CONTACT DTW APCH ON THE LANDLINE TO ISSUE US TFC; BUT THEY DID NOT ANSWER. HE THEN DECIDED TO WAIT AND ISSUE US THE TFC AFTER THE FREQ CHANGE; BUT BY THEN IT WAS TOO LATE. CESSNA DEFINITELY DID NOT MAINTAIN VISUAL SEPARATION WITH US; AND JUST AS IMPORTANTLY; THE CTLR ISSUED THE DSCNT CLRNC WITHOUT BOTH ACFT INVOLVED ACKNOWLEDGEMENTS. THE DSCNT CLRNC SHOULD NOT HAVE BEEN ISSUED.