The FBI and other officials have declined to release any information about the bomb's makeup. Knezovich said, though, that the bomb was also packed with shrapnel.
The theory is that someone hit with a piece of shrapnel covered in an anti-coagulant is more likely to bleed to death. Israeli officials have claimed in the past that Palestinian terrorists were using rat poison to make their bombs more deadly.
Whether such methods would have the intended effect, if used by the Palestinians or the person who built the Spokane bomb, remains unclear.
Authorities have not released any information about a potential suspect in the case. They are, however, calling it an act of domestic terrorism.