You say that like it would have been a bad thing, it would be much more desirable than what actually happened. Sounds like there was ample evidence that this guy should have been 5150'd, but the police were too damn something too do their job and lives were ended and affected tragically.
I'm not one to usually
Yes it would have been a better ending, but the cops don’t have precognition any better than the rest of us so nobody would realize a bigger tragedy had been prevented so they would have been criticized just as harshly for being the instigators.
“Protect and Serve” is marketing, not the job.