THE ACFT COLLIDED WITH RISING TERRAIN AT THE 4200 FT LEVEL ABOUT 3 MILES SOUTH OF ELEVATIONS OF 6800 FT. GUARDS ON DUTY WITHIN A MILE OF THE ACCIDENT SITE SAID THE WEATHER AT THE TIME OF THE ACCIDENT WAS FOGGY WITH A LIGHT DRIZZLE AND NORTHWINDS OF 35 KTS. THE ACFT CRASHED ON A HEADING OF 180 DEGREES, WINGS LEVEL, IN A DESCENT AT HIGH SPEED. THE PLT HAD CALLED ONTARIO FSS AND ASKED FOR PLT REPORTS OF WEATHER OVER LAKE HUGHES AND INTO BAKERSFIELD. THE FSS HAD NO PLT REPORTS BUT ASKED IF HE WAS AWARE OF SIGMET MIKE 7. THE PLT SAID HE WAS. HE WAS GIVEN BAKERSFIELD WEATHER AND TOLD THAT PORTERVILLE VORTAC WAS OUT OF SERVICE. THE PLT ACKNOWLEDGED THIS INFORMATION. THERE IS NO RECORD OF FURTHER RADIO CONTACT WITH THE ACFT. THE ACFT DID NOT ARRIVE AT BAKERSFIELD AND AT ABOUT 1100 PDT THE NEXT DAY THE WRECKAGE WAS SIGHTED ABOUT 19 NM WEST OF ROSAMOND.