In today's world of computers and CGI, split-screen imagery is a common way to illustrate multiple aspects of a story all at once. But there was a time, before computer wizardry, when it all had to be done by hand.
And someone had to do it first. For feature length films, that someone was Richard Fleischer - and the talented crew on The Boston Strangler.
Shot in 1967-68, the filmmakers had to literally hand-design each multi-pane shot and then assemble the footage piece by piece. It was an enormous undertaking - and one that is still celebrated for its ingenuity and foresight.
Read the comprehensive article written about it in American Cinematographer in May 2020: Multiple-Image Technique for The Boston Strangler