The Republican congressman chairs the House Homeland Security panel which held hearings last month on Islamic radicalization.
The package was discovered by mail screeners before it was delivered to King’s office.
A King spokesman says the congressman was notified of the package on Monday afternoon.
The package contained a pig’s foot and a note laced with several anti-Semitic references, according to a person with knowledge of the incident who requested anonymity because of the ongoing police investigation. King is Catholic.