What should I do about a dog not on a leash?

Well I live in a duplex and we have two neighbors. The first neighbor is nice and enjoys having us around and takes care of any problems we have, but there is another neighbor who has a big female dog who he lets out of the house when she has to do her business, but the dog doesn't have a leash on and according to the state laws(I live in Nebraska, Omaha to be precise) dogs must be on a leash at all times when they are outside no matter what. Whenever I take my dog outside, he is on a leash, but the female dog that the owner owns is not. I told my other neighbor about this and he said he would have a talk with the owner. Well, he said that he did talk to him, but every time I see the dog, she is still leashless. I really want to report him because I do not want him to get away with breaking the law and he's only had his dog on a leash once in the evening, but that's most likely because police were around and he didn't want to get into trouble. (I live by a police station) That's another thing that irks me because we live right by a police station and he somehow still avoids detection which leads me to believe that (A) the police aren't doing there job or (B) he knows how to cheat the system, so this is what I want to do. Every time his dog goes outside, I am going to take my phone camera and take a picture of the dog every time it goes to use the restroom without the leash and I am wanting to do it ten times and then report him and then show the police all of my pictures and maybe something will finally get done and the owner might get into trouble. What do you think I should do? I'm just tired of people thinking that they can get away with breaking the law.