The same research group that issued a blistering report last April on the fragmentation of St. Louis-area police departments has now issued an eye-opening report that calls for an overhaul of police training and culture.

The Police Executive Research Forum (PERF) produced the report, “Re-Engineering Training on Police Use of Force,” amid a period of introspection taking place within the nation’s law enforcement community since former Ferguson police officer Darren Wilson shot and killed Michael Brown Jr. on August 9, 2014.

That introspection has led to new thinking about issues such as officers’ mentality about their role; the generally unwritten, but widely accepted, 21-foot rule that purports to govern the legality of officers’ use of force in edged-weapon situations; and appropriate crisis intervention training and response, the St. Louis American reports.

“Some of what you will read in this report may be difficult to accept, because leading police chiefs are saying that our practices need to change dramatically,” PERF’s Executive Director, Chuck Wexler, wrote in the introduction.

Nowhere is that proposed change more evident than in police officials’ view that the profession must leave behind its warrior mentality. The role of officers should align more closely with that of guardian, the officials said.

Joseph Price, police chief in Leesburg, Virginia, responded: “We need to change that mindset, to teach officers that at times they may need to fight like a warrior, but most of the time they need to have the mindset of a guardian.”