Don't you want to solve crimes and put murderers in jail? And scare others away from delinquency?
Police brutality and systemic racism caused a group to rise up and demand justice. The populace took notice, a movement was formed (BLM) and overall trust in law enforcement was lowered. Crime rose as a result.
It's not "so called" Black Lives Matter, it's "so called" equal and just law enforcement that caused the The "Ferguson Effect"
>for every investigation over a white cop shooting a black person allegedly
This is false. Fryer saw the effect when investigations were in response to social media outrage. In fact, he called out that the effect is not seen when investigation are started in response to complaints through the regular channels.