THE OWNER, AN INSTRUCTOR PLT (CFI), WAS IN THE RIGHT FRONT SEAT & A PRIVATE PLT WITH NO INSTRUMENT RATING WAS IN THE LEFT FRONT SEAT. DURING ARRIVAL, THE AIRCREW HAD INQUIRED ABOUT THE WX AT THE ESLER REGIONAL ARPT, HOWEVER, THE FSS & THE UNICOM HAD CLOSED EARLIER THAT NIGHT & CURRENT WX OBSERVATIONS WERE NOT AVAILABLE. AT THAT TIME, THE ENGLAND AFB WX WAS CLEAR, VISIBILITY 3 MI WITH FOG. THE AIRCREW ELECTED TO MAKE AN APCH TO 'SEE WHAT IT LOOKS LIKE.' DURING AN ILS APCH AT NIGHT, THE ACFT COLLIDED WITH TREES. INITIAL IMPACT OCCURRED WITH A TREE LIMB APRX 40 FT AGL. AT APRX 0247 CDT, 2 WITNESSES HEARD THE ACFT FLYING LOW OVER THEIR HOMES, JUST BEFORE CRASHING. THEY REPORTED THE ENG SOUNDED NORMAL PRIOR TO IMPACT. ONE WITNESS, A HIGHWAY PATROLMAN LESS THAN 150 YARDS FROM THE CRASH SITE, REPORTED THE ACCIDENT & INITIATED A SEARCH, BUT WAS DELAYED IN FINDING THE ACFT DUE TO DARKNESS & FOG. THE 0300 CDT WX AT ENGLAND AFB WAS 600 FTOVERCAST, PARTIAL OBSCURATION WITH FOG. THE CFI HAD BEEN AWAKE SINCE 0400 THE PREV DAY, CONTD TRIP TO GET BACK TO WORK.