AFTER ATTENDING A BUSINESS CONFERENCE AT MUNCIE, IN, THE PLT RECEIVED A WX BRIEFING & TOOK OFF AT 2026 CST ON A FLT TO DES MOINES, IA, WHERE HE REFUELED. IN A PHONE CALL TO HIS WIFE AT THEIR HOME IN NORTH PLATTE, NE, HE INDICATED THE WX WAS SUCH THAT HE WOULD SPEND THE NIGHT AT DES MOINES. HOWEVER, AFTER CALLS TO THE FSS, HE ELECTED TO CONTINUE TO LINCOLN, NE. WHILE EN ROUTE, THE PLT REQUESTED THE GRAND ISLAND & NORTH PLATTE WX & WAS ADVISED THAT THEY WERE 25000 FT THIN BROKEN WITH UNRESTRICTED VISIBILITY.AT 0121 CST, HE EXTENDED HIS FLT PLAN TO PROCEED TO NORTH PLATTE. HE CONTINUED CHECKING ON THE CURRENT NORTH PLATTE WX. AT APRX 0218 CST, HE WAS ADVISED IT HAD DETERIORATED(CEILING 700 FT). A SHORT TIME LATER, THE CEILING DROPPED TO 600 FT OVERCAST. THE PLT DIVERTED TOWARD KEARNEY, NE, BUT THE ACFT DID NOT ARRIVE. AN INVESTIGATION REVEALED THAT IT HAD CRASHED IN A LEFT WING LOW, NOSE DOWN ATTITUDE. NO PREIMPACT PART FAILURE OR MALFUNCTION WAS FOUND. REPORTEDLY, THE PLT HAD NOT OBTAINED AN IN-DEPTH WX BRIEFING.