Obviously the more notorious the case, the more information you'll locate on it.
Whatever case you choose, however--notorious or not--make sure you give it a test drive. You always want to be sure that further into your research, you'll be able to locate all of the resources you need.
Google's a good starting place for this. It'll help you generate ideas for cases--try searching, for example, murder cases and your county, state. Or...whatever crime interests you and a location. If you throw the word notorious into the mix, you'll get larger cases or cases that have received more attention.
What other words can you think of to throw into your search (besides notorious) that may garner cases that have received more attention?
Image source Google Image, labelled for noncommercial reuse.