Attorneys started their closing arguments in a lawsuit challenging the firing of a University of Colorado professor who wrote an essay likening some Sept. 11 victims to a Nazi leader.

Ward Churchill says he was fired in 2007 because of the uproar over the essay, not over allegations of plagiarism and research misconduct as the school claims.

Churchill testified earlier in the four-week trial that the allegations about his research were false, and that the university was simply looking for an excuse to fire him. He was a tenured professor of ethnic studies.

University officials say the probe into Churchill's work was fair and his firing justified. Churchill's Sept. 11 essay was not part of the investigation against him.