Original game contents included a 30 minute audiotape containing the terrorist kidnappers' demands and other info. & clues necessary to solving the game, including news reports, recorded messages by the U.S. President and the French President while in captivity, intercepted telephone calls, an interview with the First Lady, and intercepts of morse code messages (see HERE).
Additionally, an anonymous note signed by "Saduj" (Judas in reverse) to players (who take on the role of the investigator assigned the task of solving the U.S. President's kidnapping) is also included.
TRIVIA:  THE PRESIDENT IS MISSING doesn't have a proper ending because players taking on the role of the investigator never actually "find" the U.S. President. Instead the game manual concludes by informing "victorious" players that they must write a report summarising all of the evidence and send it to the game publisher (i.e. Cosmi or MicroProse). In turn, the publisher would notify players as to whether they deduced the "correct" solution to the case.
Seemingly, neither game publisher ever shared the official solution to the game. This is much to the disappointment of game enthusiasts left in limbo, who have gathered info. toward a probable solution on this website HERE.
 THE PRESIDENT IS MISSING won the 1988 CES 'Most Innovative Software' award in Las Vegas [Source: Paul Norman, game designer].