(First two entries on this page) https://www.justice.gov/crt/statutes-enforced-criminal-secti...
i'm guessing less than 5
it's true that federal prosecutors have the freedom to prosecute local cops without themselves becoming unemployable, in a way that non-federal prosecutors do not
There was enough criminal activity under those provisions and coordinated DOJ civil litigation (which often is a product of investigations that start as criminal investigation of a specific incident, but end up discovering systemic problems in the investigated department) against local police departments under the civil provisions of civil rights law that cutting back on both was a major and public priority of the Trump Administration when it came into office in 2017.
While I can’t think of many recent notable convictions (off the top of my head, the four MPD officers convicted related to George Floyd's murder are the only ones that jump to mind), officers involved in the Breonna Taylor shooting will be going on trial under it this year (current trial date is the end of October, IIRC; the one who reached a plea deal for helping prepare the falsified warrant application pled under a more general conspiracy statute.)
But, while its not a lot of prosecutions, its enough to show that it is more than a theoretical possibility where multiple police officers deliberately act together against a Constitutional rights and leave someone dead as a consequence.