During the last week of October, 2001, ABC News, led by Brian Ross, continuously trumpeted the claim as their top news story that government tests conducted on the anthrax—tests conducted at Ft. Detrick—revealed that the anthrax sent to Daschele contained the chemical additive known as bentonite. ABC News, including Peter Jennings, repeatedly claimed that the presence of bentonite in the anthrax was compelling evidence that Iraq was responsible for the attacks, since—as ABC variously claimed—bentonite "is a trademark of Iraqi leader Saddam Hussein's biological weapons program" and "only one country, Iraq, has used bentonite to produce biological weapons."
ABC News' claim—which they said came at first from "three well-placed but separate sources," followed by "four well-placed and separate sources"—was completely false from the beginning. There never was any bentonite detected in the anthrax (a fact ABC News acknowledged for the first time in 2007 only as a result of my badgering them about this issue). It's critical to note that it isn't the case that preliminary tests really did detect bentonite and then subsequent tests found there was none. No tests ever found or even suggested the presence bentonite. The claim was just concocted from the start. It just never happened.
That means that ABC News' "four well-placed and separate sources" fed them information that was completely false—false information that created a very significant link in the public mind between the anthrax attacks and Saddam Hussein.
If you could dial the Wayback Machine to late 2001, you could find a lot of these linkages that never panned out.