Try Holder’s office or his THUGS paid for and run
by the DO”J”.
That means Holder's DOJ will be of no help in this.
However, all is not lost. ATF and FBI aren't the only guys who investigate bombs. USPS has postal inspectors fully versed in the arcane science of deducing the identity of the originator of a bomb.
Right off hand they'll be checking the device and its packaging for fingerprints as well as traces of sputem, et al, with DNA!
Then, along the way someone will find a RETURN ADDRESS.
Ah, yes, the downfall of many a mad bomber ~ the return address ~ yes, that happens ~