When Inspector Carella starts the tape to interview Patricia, he asks her what occurred on the night of September third, which one might assume is Saturday, the third of September, 1977. But in the very next scene another detective is interrogating Andrew as to the events of Saturday the twelfth. This is nine days later, not the date given by Carella, and was a Monday. It is clear from the context in the film that the murder occurred on a Saturday, as the next day was Sunday, for when the Inspector was in the park with his daughter, church bells could be heard. In addition, the following day when the Inspector goes to interview Jean Hanley, she admits to intending to return to school later that day, thus, that was Monday.