Ask Marilyn ® by Marilyn vos Savant is a column in Parade Magazine, published by PARADE, 711 Third Avenue, New York, NY 10017, USA. According to Parade, Marilyn vos Savant is listed in the "Guinness Book of World Records Hall of Fame" for "Highest IQ."
In her Parade Magazine column of July 1, 2007, Marilyn applies faulty logic to solve a logic puzzle.
Her error is assuming that "the evildoer arrived before me" being false implies "the evildoer arrived after me" is true. It actually implies "the evildoer arrived after me, or I am the evildoer" is true.
Thus, while her solution is valid, it is not the only solution, and her explanation is wrong.