A criminology course at the University of Northern Colorado is the setting for one of David Horowitz's favorite stories.

As he tells it, a required essay on a mid-term exam was for students to "explain why George Bush is a war criminal." A student submitted an essay on why Saddam Hussein was a war criminal and she received an F.

But a number of blogs and columns have noted in recent days that neither the student nor the professor can be found. Links set up from Horowitz's writings on the subject to Colorado legislative hearings where he says the incident was discussed feature no discussion of the incident.

Mano Singham, director of Case Western Reserve University's Center for Innovation in Teaching and Education, spent some trying to track down the course and the student, and wrote about the experience for The Plain Dealer, finding no evidence of any such incident at the university in question or in Colorado legislative records.

"So does this mysterious professor actually exist? Did this incident actually happen? It is hard to say no for certain, since that involves proving a negative. But there are some characteristics of urban legends that this story shares, in particular the absence of details (names, places, dates) that enable one to pin it down to anything concrete," Singham wrote. "Given that Horowitz and his group have shown no scruples in the past about naming people in academia that they dislike, their sudden coyness in this particular case is a little surprising."

Many professors believe that the "Academic Bill of Rights," proposed by Horowitz and his supporters in many state legislatures, would encourage harassment of professors and monitoring of their views. But Horowitz has repeatedly justified the legislation by pointing to examples -- like the alleged Northern Colorado student -- to say that legislation is needed.

A good compilation of the online discussions and evidence in the case was posted Friday on the blog Cliopatria by Jonathan Dresner, an assistant professor of East Asian history at the University of Hawaii at Hilo. Dresner found it "particularly odd" that "Horowitz's own site has links which appear to be citations but which go to hearings in which the testimony in question clearly doesn't appear."

He added, "There's plenty of good material for Horowitz in those hearings so you wouldn't think he'd need to make something up.... I suspect that he's been caught up in an urban legend that he can't let go of, and used the links as a sort of meaningless footnote."

In an e-mail interview, Horowitz said that the incident was reported to a Colorado student involved in his group Students for Academic Freedom. Horowitz said that the student "has fiercely protected the identity of the student who made the complaint," but said that he was working to get the name of the student and the course so he could provide them.

He went on to say that there are "hundreds of examples of this kind of harassment and intimidation on our Web site," and that many students "have nowhere to turn" when their professors punish them for their views. He said that those attacking him over the Northern Colorado example online are part of the "legions of left-wing academics who are in extreme bad faith on this issue, since they are collusive in a repressive system and haven't uttered a peep on behalf of students who disagree with them politically."

He added, however: "I consider this an important matter and will get to the bottom of it even if it should mean withdrawing the claim."