Ok, first link in results contradicts "slave patrols led directly into being police departments in some parts of the US":
While it is true that slave patrols were a form of American law enforcement that existed alongside other forms of law enforcement, the claim that American policing “traces back” to, “started out” as, or “evolved directly from,” slave patrols, or that slave patrols “morphed directly into” policing, is false. This widespread pernicious myth falsely asserts a causal relationship between slave patrols and policing and intimates that modern policing carries on a legacy of gross injustice. There is no evidence for either postulate.
> What is the source of this data?
https://duckduckgo.com/?hps=1&q=police+departments+were+conv...