THE ACFT CRASHED INTO THE TOP OF A MESA AT THE 5500 FT LEVEL (MSL). THE ACFT THEN CARTWHEELED ABOUT 300 FT ON A HEADING OF 360 DEGREES. SHERIFFS DEPUTIES DISCOVERED AT THE ACCIDENT SITE THAT THE ACFT WAS LOADED WITH MARIJUANA WEIGHING ABOUT798 LBS. AN ADDITIONAL AMOUNT OF MARIJUANA ESTIMATED AT 200 LBS WAS SCATTERED ALONG THE WRECKAGE PATH. TWO BODIES WERE RECOVERED AT THE SCENE. NEITHER WAS THE PLT WHO HAD RENTED THE ACFT. THREE DAYS AFTER THE ACCIDENT THE PLT WHO HAD ORIGINALLY RENTED THE ACFT REPORTED THE ACFT STOLEN. IT WAS NOT DETERMINED IF THERE WAS A CONNECTION BETWEEN THE RENTER AND THE DECREASED ACFT OCCUPANTS. THE PILOTS BODY TESTED POSITIVE FOR ALCOHOL & DRUGS, WITH AN ALCOHOL LEVEL OF 0.066%. PERCENT. THE ACFT WAS HEADED DIRECTLY TOWARD THE ROTATING BEACON AT CANYONLANDS ARPT, ELEVATION 4574 FT MSL. THE DENSITYALT WAS COMPUTED TO BE 5359 FT AT THE CRASH SITE AT THE TIME OF THE ACCIDENT. THE DEPARTURE POINT AND THE DESTINATION OFTHE ACFT WAS NOT DETERMINED. THE ACFT WAS SCHEDULED TO BE RETURNED THE DAY AFTER THE ACCIDENT BY THE ORIGINAL RENTER.