MIA89FA100

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.