THE PLT (A PART TIME EMPLOYEE OF THE OWNER) WAS FERRYING THE ACFT FOR MAINTENANCE. WITNESSES, WHO SAW THE PLT BFR TAKE- OFF, NOTED THAT HIS SPEECH WAS SLURRED & THAT HE SEEMED ANGRY BECAUSE A TUG WOULD NOT START. ONE WITNESS CHARACTERIZED HIM AS BEING 'VERY MAD' & SAID HIS FACE WAS 'FLUSHED RED.' THE ACFT WAS OBSERVED TO TAKEOFF IN A HI NOSE-UP ATTITUDE & CLIMB ABOUT 500 TO 1000 FT BFR TURNING TO THE SW & LEVELING. SUBSEQUENTLY, THE PLANE TURNED BACK TOWARD THE ARPT, THEN IT CRASHED & BURNED APRX 1-1/2 MI SSW OF THE ARPT WHILE ON A HDG OF NE. IMPACT OCCURRED WHILE THE ACFT WAS DSCNDG IN A SLIGHTLY LEFT WING LOW ATTITUDE. THE WRECKAGE WAS SCATTERED OVER AN AREA THAT WAS APRX 600 FT LONG & ABOUT 45 FT WIDE AT THE WIDEST POINT. ACCORDING TO WITNESSES, THE ENGS WERE OPERATING NORMALLY WHEN THE ACFT CRASHED. NO PREIMPACT MECHANICAL PROBLEM WAS FND. A TOXICOLOGY CHECK OF THE PLT'S LIVER TISSUE FLUID SHOWED AN ALCOHOL LVL OF 0.226%.