Then quietly forgotten, but if asked, the findings will be,"We have found the officers actions comply all with all Dept Policy and Directives", "The officers actions were justified and corroborated by independent sources(never actually stating the sources because of privacy issues )".
At worst, "The officer has been counseled and administrative discipline has been taken(never actually explained, probably moved and promoted)".
If it is so outlandish the Dept simply can't evade, cover up or justify the problem with an amount of bullshit, "The officer has suffered or was suffering from a medical or mental condition and has since been given a medical discharge with full pension. No further action can be taken in this case by the Dept."
They don't administer the law, they are the fucking law.