Depends on jurisdiction. Most require an associates degree which is a 60 credit degree, but it can't be 60 "loose" credits. You can sneak your way in often around that by applying to be a corrections facility guard, which usually doesn't require it, but you can still transfer to an officer in some places after a year. its a better deal for someone younger (not sure how old you are) as the starting pay sucks and the real benefits of doing it largely come after many years of service. Well, plus given how some of the cities and states are doing, the whole idea of staying 20 years to retire on a nice pension may not actually work out for you.