See the full publication here:
http://leagle.com/decision/In%20FDCO%2020150428A80/U.S.%20v.%20BATES
Concrete proof, at last, that law enforcement does use - routinely, it seems - logged IP address information from USPS' website and tracking service as part of their investigations .
In other words: Don't track that crack!
This headline is a little misleading. It implies the tracking led to the investigation. The way I read it, they found the powder then started monitoring tracking.
There is also some interesting stuff in there about how he used someone else to pick up the package, and how that really provided no protection at all.