REPORTEDLY, THE PLT HAD CALLED THE ARPT OFFICE (UNICOM) & WAS ADVISED THAT RWY 15/33 WAS CLOSED. AT ABOUT THE TIME N3354F WAS ARRIVING, A MILITARY HELICOPTER LANDED ON RWY 27. THE PLT ASKED A PASSENGER TO TELL HIM WHICH WAY THE WIND SOCK WAS BLOWING & SHE REPLIED THAT IT WAS 'FLYING WEST.' THE PLT ELECTED TO LAND ON RWY 27 WHICH HAD A 533 FT DISPLACED THRESHOLD & HAD A DOWNHILL GRADE OF 1.52%. WITNESSES REPORTED THAT THE ACFT WAS FAST ON FINAL APCH & LANDED LONG. SUBSEQUENTLY, IT WENT OFF THE RGT SIDE OF THE RWY, NEAR THE DEPARTURE END, HIT A RWY LIGHT & CONTINUED ACROSS ROUGH TERRAIN. THE PLT APPLIED POWER & THE ACFT BECAME AIRBORNE AT THE EDGE OF A WIDE GULLY AREA. IT THEN SETTLED & IMPACTED A DIRT BANK AFTER CROSSING THE GULLY. SKID MARKS FROM THE ACFT WERE FOUND STARTING ABOUT 1366 FT FROM THE DEPARTURE END OF THE RWY & CONTINUED UNTIL THE ACFT LEFT THE RWY. NEARBY AT THE JEFFCO ARPT, THE 1145 MST WIND WAS FROM 140 DEG AT 14 KTS. THE DENSITY ALT AT THE CRASH SITE WAS APRX 6100 FT.