Riot Guards are armoured guards, called via the Emergencies Tab, that are better able to deal with violent situations than regular Guards or Armed Guards. Like Armed Guards, Riot Guards will raise the suppression level of the prison.
Riot Guards should be used only to deal with full scale Riots, not with day-to-day situations of your prison. Thus, you should not have them as full-time staff of your prison.
When a Riot breaks out, use the Emergencies Tab to call the Riot police. Riot Guards can be selected quickly or dismissed through the Squad list on the right hand side of the screen. Riot Guards need to be told where to go to deal with the prisoners. To do so click on a officer and right click to tell him where to go.
Riot Guards are tougher than Armed Guards, but they only have a baton and a shield, where the Armed Guards have shotguns (and also require the armory where prisoners can get powerful weapons in their inventories) Of course a disarmed Riot Guard means a prisoner with a baton, where a disarmed Armed Guard means a prisoner with a shotgun.
The Riot Guard is seen once with a battering ram in chapter 3 G.A.B.O.S. but the battering ram is unobtainable in any other part of the game.
They were in the game from Alpha 1 as an additional guard type for your prison. They had to be researched via Bureaucracy, and their actual function would be added to the game in a later version. But in Alpha 10 the devs decided to put the Riot Guards as Riot Police under the Emergencies tab, where you can use them to battle riots when regular guards are not enough.
If the police vehicle does not depart when dismissed there may be a tree on the road blocking the path, simply dismantle it. It is advised to make sure you get the Riot Officers out of a fight when you dismiss them, otherwise they might decide they can't leave safely and will keep on fighting.
If a riot police squad goes into the prison and goes into the captured zone. They would get stuck and are unable to move until the zone is recaptured, forcing them to go somewhere else will not work and Dismissing them will not work. (Fixed as of update 12)