If all 6 cops on the scene unanimously participated in the torture and murder of a disabled man in plain view of the public, the problem is not just these 6 killers. The entire police culture is the problem.
Statistically, if all 6 at the scene did this, then nearly everyone on the Fullerton police force would have done the same. These 6 are not exceptions who just happened to come together.
Much of the problem is coming from Dept of Justice training initiatives like the DOJ's Preventing Violence Against Law Enforcement" initiative, as well as the federal encouragement of militarization of police depts.
Officer injuries and disability are a big issue for police departments these days. They do not want officers on disability over an injury resulting from having to subdue a suspect. Google "officer safety" training. To an increasing extent, training is focusing on making officer safety the #1 priority.
If officers are trained to think that "officer safety is priority #1", then that means that the safety of public interacting with officers is a lower priority, with predictable results. This is what you get when you transform a profession which had "To protect and to serve" as its motto, into just another union job.