DRG ARR, APCH CTL PROVIDED VECTORS & CLRD THE PLT FOR AN ILS RWY 7L APCH. AS THE ACFT CONTD, THE CTLR NOTED IT WAS APRX 1 MI 'SOUTH OF FINAL' & ASKED THE PLT IF HE WAS RCVG THE LOCALIZER. THE PLT SAID NO. THE CTLR THEN BGN GIVING INSTRNS FOR A SURVEILLANCE APCH & TOLD THE PLT THE MIN DSCNT ALT (MDA) WAS 420', BUT DID NOT CLR HIM TO DSCND. SOON THEREAFTER, THE CTLR NOTED THE MODE C READ-OUT (WHICH HAD BEEN INTERMITTENT) WAS INDCG 400'. THE CTLR IMMEDIATELY TOLD THE PLT TO TURN LEFT TO 360 DEG & CLIMB TO 1600' & THE PLT ACKNOWLEDGED. THE CTLR THEN ADZD THE PLT THERE WAS AN ANTENNA AT HIS ONEO'CLOCK PSN, BUT THERE WAS NO RESPONSE & CONTACT WITH THE ACFT WAS LOST. LATER, THE ACFT WAS FND IN THAT VCNTY WHERE IT HAD HIT TREES & CRASHED ON A HDG OF 160 DEG (1.6 MI WSW OF THE OUTER MARKER, TERRAIN ELEV APRX 35'). THE UNDMGD #1 NAV WAS FND TO BE SET AT 109.75 MHZ. THE ILS FREQ WAS 109.7 MHZ. THE PLT'S ESTD FLT TIME IN THE BEECH S35 WAS 10 HRS; HIS CFI BELIEVED HE WAS NOT CURRENT FOR INST FLT. THE 1342 EST WX AT THE ARPT WAS 300 FT OVC, 2 MI VIS WITH FOG & DRIZZLE.