OP frankly speaking, your story is technical and confusing me. You said, you did not know or have no idea on bitcoin or Wallet but from your discovery of the paper wallet, you noticed that it contained 0.6 BTC which you confirmed that it is bitcoin from the first sight, as for only that statement indicate that you have an idea on BTC because someone that does not know BTC would recognized it unless he or she asked someone that knows Cryptocurrencies or if you don't Know it, you would have left it behind as other passerbys did. But you were fully aware that it was BTC that is why you picked it.
That is not withstanding, there is no way you can see the owner of the wallet. Because probably the owner had been looking for it all this while but no avail. And the only way the owner of the wallet can found it is for you to go the local Radio Station and make the announcement for the lost wallet. And I don't think you have money to pay the media unless the media will not take money from you. Since you have brought it here, I advise you to do that. I do not think, the wallet was stolen but was lost from the owner.