What should be done to get my dog back?

While out of town my brother agreed to watch my chi. He lives in an apartment complex area, he allowed my dog to run out for exercise and play. While he attended to the yard my dog came up missing ... after searching for a couple days or so...putting up flyers and so on. I went out to my bros apt and decided to look again...going door to door came upon a neighbor who told me the neighbors living directly across had a similiar dog, that they havent had before. I went over to ask Qs the neighbors cousin denied having seen a dog. My neighbors protested saying they are sure they were seen with the dog, they didnt speak much english, so I had a friend translate for me, the dog was seen with the neighbors across the street. 2 days later these ppl moved and I have yet to see my dog again. Is there anything I can do?