My suggestion is that someone should go and claim it ASAP (even if it doesn’t belong to you – I mean how hard can it be to claim tefillin?), and then bring it to the New Square Hashavas Aveida organization. That way, we know it’s in safe, Jewish hands and will not be risked being disposed of in an unacceptable way. And they will try and find the owner.
I would go myself, but I think someone who actually works/lives in that neighborhood should go.