you don't, which is the point. while comey were still a respected director o' fbi with many years o' exemplary service and bipartisan support, he were asked 'bout gun violence statistics while testifying before Congress. comey couldn't give answers 'cause he didn't have answers. the head o' fbi did not have accurate numbers for gun violence in the US. just one example. fbi isn't what oro thinks it is, and it sure as hell doesn't manage or coordinate state and local police.
folks need to learn there ain't no The Police in the USA. even americans is woeful misinformed 'bout the authority the fed has over local law enforcement practices, training, spending and activities.
the intent o' US system is for police to be more direct answerable to the people who vote in sheriffs or city council/mayor elections. the further is the seat o' power from which police is directed, the greater the potential for abuse, or so believed the framers. what is to stop the Fed from sending in a national police if the issue in question is localized to portland? for better or worse, mayors and sheriffs in portland is gonna be far more sensitive to citizens o' portland than will the President or william barr.
as to insurrection act, don't rely on fox. when used in past, the act has almost always been utilized by the President with approval o' a state governor, the main reason being you either need governor approval, or the activities being curtailed by the Fed need be o' a type and nature it is impracticable for states to address. is not simply a matter o' state unwillingness to use heavy-handed force which triggers. some function o' scope or type must make implausible for local to handle the matter.
HA! Good Fun!