Lots of speculation
This story is getting lots of coverage elsewhere. It's uncertain, and is not likely to become public soon, whether or not the recovered wreckage has a radar absorbent coating. And the NYT article implies that the tail section could not have come from an MH-60 (special ops Blackhawk). It's definitely different, but still about the right size. There's speculation that there's a secret, stealthy version of the MH-60 in use - stealthy on the outside but basically the same on the inside. Or it might also be a another mid-size helicopter, such as a Sikorsky S-92, with stealth features added, but it's unlikely to be a totally different design.