There is this creepy guy who robs in my neighborhood, a lady tried to arrest him, but she cancelled it for some reason. Everybody is scared of him and we haven't done anything to call the cops. What should we do?

Wait ... Are you saying homes are being robbed and no one is reporting it? Whether or not it's "this guy" is irrelevant ... Robberies should be reported so they can investigated .. Let the police do the rest. No one had to catch him in the act to report it. If it in fact "this guy" the police will handle it.

Call the cops.

You need to call the police.....I highly doubt a "citizens arrest" would do any good.....although it is funny!