THE HELICOPTER WAS ON A RESCUE/RECOVERY FLT FOR THE ALASKA STATE TROOPERS WITH THE PLT & A STATE TROOPER ON BOARD. THEY DEPARTED IN VARIABLE WX CONDITIONS TO RESCUE THE PLT OF ANOTHER ACFT. REPORTEDLY, SNOW WAS FALLING IN THE SEARCH AREA & THE WINDS WERE GUSTING BETWEEN 70 & 90 MPH. ACCORDING TO THE PLT, THE ENG FLAMED OUT DURING A TURN AT APRX 1000 FT AGL. HE BEGAN AN AUTOROTATION & TRANSMITTED A DISTRESS CALL. DURING AN APCH TO A FROZEN RIVER, HE ENCOUNTERED A TOTAL WHITEOUT CONDITION IN FOG & BLOWING SNOW AT APRX 75 TO 100 FT AGL. HE GUESSED AT THE ALT TO APPLY COLLECTIVE PITCH TO STOP THE DESCENT & SAID THAT HE EXPERIENCED VERTIGO DURING THE LAST PART OF THE DESCENT. THE ACFT IMPACTED IN A LEFT, NOSE DOWN ATTITUDE & ROLLED OVER. THE OCCUPANTS WERE UNABLE TO REACH THEIR SURVIVAL GEAR IN THE WRECKAGE. WX DELAY THEIR RESCUE & THE PASSENGER DIED FROM HYPOTHERMIA. THE ACFT WAS EQUIPPED WITH PARTICLE SEPARATORS, BUT NO SNOW DEFLECTORS WERE INSTALLED. NO MECHANICAL ENG FAILURE WAS FOUND, BUT A COATING OF ICE WAS FOUND IN THE ENG INLET.