What a weeeird plot... never heard of this one. I was wondering if you were conflating elements of two 90s films about investigators - THE SWEET HEREAFTER and the totally nonsensical EYE OF THE BEHOLDER (a remake of a slightly more cogent French film, DEADLY CIRCUIT, from the early 80s) - both of which suggest the sort of parallel you describe to some extent. Neither of them actually has that plot, though - and I'm somewhat surprised to hear that any authentic film does!