<human>:  I have a question about the movie Case history. Why did the narrator say that the movie was based on a true story?
<bot>: The narrator was referring to the fact that the movie was based on a true story. The movie is based on the true story of the case of the Central Park Five, a group of young men who were accused of raping a woman in Central Park in 1989. The case was controversial, and the five men were eventually exonerated.