ELKO DME (LOCATED AT THE ARPT, USED FOR THE LDA/DME APCH, 108.5 MHZ) WAS INOP. DRG ARRIVAL, THE PLT EXPRESSED MISTRUST OF HIS DME. APRX 24 MI SSE OF BULLION (BQU) VOR, ARTCC CONTROLLER (CTLR) CLRD N7514N FOR 'THE APCH TO THE ELKO ARPT.' SECONDS LATER, THE PLT SAID HE WAS IN A DWNDFT, DIDN'T HAVE DME TO THE ELKO VOR & ASKED IF HE WAS CLR OF THE RUBY MTNS. CTLR ADVISED, THE ACFT WAS STILL 24 MI SOUTH (WHICH WOULD HAVE BEEN OVR MTNS). APRX 90 SEC LATER, THE CTLR ADVISED DME WAS OUT OF SVC & THE PLT WAS CLRD FOR VOR-A APCH. PLT ACKNOWLEDGED. AT THAT TIME, THE ACFT TURNED SOUTH W/O CLNC, THEN CONTD TURNING BACK NORTH. CTLR TRIED TO CONTACT THE PLT ABOUT THE DEVIATION, BUT THE PLT HAD CHANGED TO FSS FREQ W/O CLNC. THE ARTCC CTLR NOTED DSCNDG FLT OVR MOUTAINOUS TERRAIN, CONTACTED THE FSS & LEARNED THE PLT WAS ON THE FSS FREQ. HE RELAYED AN ADVISORY OF THE ACFT'S PSN, BUT DID NOT GIVE SPECIFIC INSTNS FOR IMMEDIATE CLIMB. ACFT CRASHED IN MTNS, ELEV 10,200', APRX 19 MI SSE OF THE ARPT. MTNS WERE OBSCD BY CLDS. PLT HAD RECD AN INSTRUMENT RATING ON 3/13/85.