NYC89FA204

The plt was repositioning the acft at ngt to his home arpt at kingston. He rcvd VFR advisories fm new york TRACON for routing to teterboro & to cont north below the tca, along the hudson river to kingston. The ATC ctlr issued a clnc as requested, provided wx info & told the plt to maint 2500'. Minutes later, the plt requested a lower alt & was approved for flt thru the teterboro arpt tfc area. He rprtd 'the george Washington bridge in sight' & said he no longer needed radar svc. At 2222 EDT, radar svc was terminated 2 mi east of teterboro & there was no further radio ctc with the acft. Subsequently, it hit trees & crashed near a hilltop, while hdg sw over an artillery range on the West Point military academy. Radar data showed that after radar svc was terminated, the acft contd north btn 1800' & 1200' MSL until radar ctc was lost aprx 3 mi south of the artillery range. A witness (2 mi south of the crash site) saw an acft circling at low alt before continuing north. She said conds were rainy, cloudy & very dark. No preimpact mech problems were found.