If you need to pick a topic, try going to the National Criminal Justice Reference Service (NCJRS). This is a great place to explore potential topics in criminal justice.
After you pick your topic, it's important to narrow it down so that it's researchable. If your topic is too big, you'll get too many results when you start looking for sources. In order to narrow your topic and brainstorm what is interesting to you, ask yourself the following questions. You don't have to answer all of them but answering at least a couple will help you define your topic in a more research-able way.
WHO is interested in this topic? WHO does it relate to? (Be specific and pick particular population.)
WHERE is your topic relevant? WHERE in the world/country do you want to focus? (Again, be specific. Pick a city or state.)
WHAT is interesting to you? WHAT are some subtopics? WHAT do you want to learn?
WHY is this topic important? WHY are you interested in this topic?
Before diving into in-depth research, it's helpful to get background information on your topic. Encyclopedias and dictionaries are good places to start. They offer reliable background information and can also help you find a research topic. Use the following databases to find background information on your topic.
After you've thought about ways to narrow your topic, you can brainstorm keywords and different aspects of your topic. These keywords and the subtopics you brainstorm become the words you use when you search for information.