The purpose isn't to prosecute protesters, it's variably to intimidate and rile them up. It isn't to hold protesters accountable for their actions, it's a setup

The purpose isn't to prosecute protesters, it's variably to intimidate and rile them up. It isn't to hold protesters accountable for their actions, it's a setup for a win-win scenario: (a) stop protesting and start complying means the secret police win; (b) fighting back with force means the secret police win. The only way they lose is with scrutiny, so avoiding scrutiny is their top priority. Hence the secrecy. Any U.S. attorney charged with the task of defending police in any of these cases will be ordered to obfuscate, delay, and confuse the issues.