> The leading hypothesis for why these [police shooting protests] increase homicides and total crime is an abrupt change in the quantity of policing activity. In Chicago, the number of police-civilian interactions decreased by almost 90% in the month after the investigation was announced. In Riverside CA, interactions decreased 54%. In St. Louis, self-initiated police activities declined by 46%.

This is from a 2020 paper from Harvard’s Roland Fryer and Tanaya Devi: https://www.nber.org/system/files/working_papers/w27324/w273...