THE PLT AND 3 PAX BOARDED THE ACFT AT ANGEL FIRE, NM (ELEV 8382 FT MSL) TO RETURN TO PHOENIX, AZ. DENSITY ALT WAS APRX 11,582 FT MSL. THE ACFT, WHICH HAD JUST BEEN SERVICED, HAD 54 GAL OF FUEL ON BOARD AND WAS APRX 30 LBS OVER ITS MAX GROSS WEIGHT LIMIT. THE PLT ELECTED TO TAKE OFF ON RWY 17 (8900 FT X 75 FT, 0.643% UPHILL GRADIENT). HE ROTATED 3 TIMES BEFORE THE ACFT FINALLY LIFTED OFF NEAR THE DEPARTURE END. NUMEROUS WITNESSES OBSERVED THE ACFT FLYING LOW THROUGH THE VALLEY TOWARDS GRADUALLY RISING TERRAIN. IT FINALLY STRUCK TREES AND CRASHED APRX 5 MI FROM THE ARPT AT AN ELEV OF 8813 FT MSL. ONE PAX WAS FATALLY INJURED WHILE ATTEMPTING TO EVACUATE THE BURNING ACFT. PERFORMANCE CHARTS INDICATED THE ACFT WAS CAPABLE OF TAKING OFF UNDER THE PREVAILING CONDITIONS. THE PLT LATER REPORTED THAT TURBULENCE AND DOWNDRAFTS DEGRADED THE ACFT'S CLIMB PERFORMANCE. HE ALSO INDICATED THE ACFT WAS ON THE VERGE OF STALLING THROUGHOUT THE SHORT FLT.