The package never actually reached King's office--it was scanned beforehand and pulled aside.
We're no forensics experts, but barring any deliberate attempt to mislead people, it seems like the anti-Semitic note would rule out any Jewish suspects, and the pig's foot itself probably wouldn't have come from a Muslim.
http://www.theatlanticwire.com/politics/2011/04/someone-mailed-rep-peter-king-bloody-pigs-foot/36336
