After spending much of Monday explaining his political opinions, the former professor, Ward L. Churchill, faced extensive cross-examination by the university’s lawyer, Patrick O’Rourke.

A faculty committee concluded that Mr. Churchill had plagiarized and fabricated sections of his work on the persecution of American Indians, leading to his dismissal in July 2007, the university says.

But Mr. Churchill maintains that he was forced out because of the controversial essay, in which he characterized workers in the World Trade Center as “little Eichmanns.”

In a back-and-forth that was intermittently cutting and congenial, Mr. O’Rourke delved into the details of Mr. Churchill’s work, much of which focused on the spread of smallpox among Americans Indians and assorted aspects of law affecting Indian country.

Mr. O’Rourke said Mr. Churchill’s admission that he had ghostwritten works for other scholars and occasionally cited them to support his own theories clearly violated academic standards, as the faculty committee had concluded.