The 1971 disappearances ...
So the New York detective had a crime board, with details of 50 or so disappearances (according to a newspaper headline), and we saw that 3 of them were from 1971, and one from 1997.
SPOILERS
But what did all that have to do with the crimes portrayed in the movie.
And why did the detective mention that they were in a bayou which linked all the crime scenes. Was he just covering up his source in the phone company, or was he actually claiming to have discovered some clue from all his mapping?