Perhaps he's simply walking for health reasons or to get away from a bad home environment. It sounds like it's a regular pattern for him.
If you are concerned, just strike up a friendly conversation with him and tell him that you've seen him a lot and hope he enjoys his walks. If he's up to no good, he'll know he's been spotted and won't be back. If he's just out walking, you've made a new friend.
Please note that this response is based upon the limited information available in the question. In addition, it is not intended to create an attorney/client relationship and is offered only as general information and not as legal advice.