On April 20, 1997, at 2105 eastern daylight time, a Beech 95-C55, N242BS, was observed on radar to descend from 10,000 feet mean sea level (msl) until being lost on radar, about 3,000 feet msl. The location was about 13 miles west of Grand Haven, Michigan, over Lake Michigan. Debris was located in that general area, on the surface of the lake. The airplane is presumed to be destroyed. The pilot and one passenger are presumed to have sustained fatal injuries. The 14 CFR Part 91 personal flight was operating on an IFR flight plan. Visual meteorological conditions prevailed at the closest land-based weather reporting station to the impact location. The flight departed Marshall, Michigan, about 2030 with a planned intermediate stop of Medford, Wisconsin, and final destination of Fargo, North Dakota. An individual identifying himself as the pilot-in-command of N242BS contacted the Lansing (Michigan), Federal Aviation Administration (FAA), Automated Flight Service Station (AFSS), at 1908 requesting an IFR route briefing from Marshall, Michigan, to Medford, Wisconsin. A transcript of that conversation is attached as an addendum to this report. There was no forecast for IFR conditions, severe weather warnings, warnings for ice or turbulence along the route of flight or at the planned destinations. At the end of the briefing the pilot filed an IFR flight plan with an intended departure time from Marshall of 1935. In that flight plan the pilot requested a cruising altitude of 10,000 feet msl and he stated that there was an anticipated fuel endurance of four hours. The first recorded radio contact with the Grand Rapids (Michigan), FAA, Air Traffic Control Tower (ATCT), Arrival Radar, occurred at 2030, when the pilot of N242BS radioed to obtain the IFR clearance and routing to the initial destination, stating, "Two four two bravo sierra's off Marshall, IFR to mike delta zulu." The pilot received an IFR clearance from the ATCT. At 2103, the pilot called the ATCT requesting, "... do you get me on radar with... ?" There were no further recorded radio communications with N242BS. The transcripts from communications between N242BS and the ATCT are attached to this report. A "Recorded Radar Study" was conducted by the NTSB Office of Research and Engineering from data supplied by the FAA Air Route Traffic Control Center (ARTCC). The data shows N242BS, at 2105, in a descent from 10,000 feet msl until being lost on radar about 3,000 feet msl. During this time no radio communications were recorded from N242BS. The complete study is attached to this report. No eyewitnesses were located who stated seeing the airplane in flight during this timeframe. Debris was located on the surface of Lake Michigan, about 13 miles west of Grand Haven, Michigan, on and after April 21, 1997. The debris was presumed to be from N242BS.