They may get cleared by an investigation, but they're still blamed by the public. Pretty sure that's Calron's point. As an example, the fatal shooting of Charles Landeros at his daughter's middle school.
The officers were completely justified, since Landeros pulled a gun on them and fired off a couple of wild shots... at a friggin' school, with his own daughter watching, and he wasn't even supposed to be there due to a custody dispute. The guy was endangering the lives of not only the cops, but his own daughter and the other children at the school.
None of that mattered though, protesters showed up in force and blamed the cops.