The Boondock Saints: Lighting and Setting

The setting in the Boondock Saints took place in Boston; it never said the date but I'm guessing it took place in 1999, in March (the very first day on the movie started on St. Patrick's Day). The lighting in the movie was overall realistic, with no shade over the whole movie, which gave a...realistic feel. What I found interesting was that when the two protagonists in the movie would kill and/or execute someone, the lighting would remain the same. But when the protagonists would perform their sacred ritual of putting pennies in the eyes of the dead, to give access to the River Styx in the afterlife, the lighting would turn black and white. There were most dolly shots, too.