Does anyone know how long fingerprints can last on a plastic bag? I think it will be very difficult to prove that the fingerprint was put on the bag while the detonators were in the bag. I suspect he will argue that he sent a bag to Spain. The bad guys re-used the bag to hold whatever.
Also, I think US cell phones will not work in Europe, so if the claim is that he shipped cell-phone based detonators to Europe, the prosecution is going to have a tough time.
T-Mobile, part of the Deutsche Telekom behemoth, offers SIM cards in the US.
As I understand, T-Mobile has penetrated the US market very effectively in the Pacific Northwest.
SIM cards figure prominently in the Madrid bombings.