If I'm not mistaken, Earth Day had its genesis in Philadelphia. At any rate, there was a Woodstock-like mass Earth Day gathering there in a huge public park overlooking the denser part of the city.
The Earth Day leader was a loudmouth named Ira Einhorn, who had a following of hippies as well as academics and other left wingers. Einhorn not too much later murdered his girlfriend, sealed her body in a trunk and fled to France.
The body eventually dripped through the ceiling below and a manhunt was on. Einhorn underwent plastic surgery in France, married a Frenchwoman and lived the wine and cheese life for many years. Even after he was eventually caught, France refused to extradite him because the U.S. still had the death penalty. He wasn't returned to the U.S. until many years after the murder.
I think he is still rotting in prison in Pennsylvania finally, though, thanks to past Philly D.A. Lynne Abraham.