ENVER, March 25 - Prof. Ward L. Churchill cannot be fired from his job at the University of Colorado for controversial opinions like his comparison of some victims of the Sept. 11 World Trade Center attack to Nazi technocrats, the university said in a report released late Thursday.

But the professor could be fired if accusations of academic misconduct, including plagiarism, are borne out, the report said.

The report, by the university's interim chancellor, Philip P. DiStefano, is a fork in the divisive debate over Professor Churchill, whose name has become a rallying cry across the political spectrum in the past few months, ever since an essay he wrote shortly after the Sept. 11 attacks became widely known.

In the essay, Professor Churchill said that some trade center workers were active players in the United States' economic and foreign policy apparatus, which he said provoked the attack. He called them "little Eichmanns," in reference to the Adolf Eichmann, a crucial figure in the Nazis' campaign to exterminate Jews.

After the essay's release, several politicians, including Colorado's governor, Bill Owens, a Republican, called for the professor to be fired.

The resulting inquiry, begun in early February mostly as an examination of academic free speech, has evolved into something broader, people on the campus say.

Detractors of Professor Churchill came out of the woodwork, questioning his claim to be part Indian, the integrity of his research and the originality of his academic writing.

The professor's supporters said that free speech was still the central issue, and that his critics were looking for ways to justify what would be a politically motivated firing.

The chancellor's report split those questions in two: the free speech question is settled, but the matter of Professor Churchill's academic record is not.

The university wants to examine his writing and speeches for evidence that he misrepresented his background and did not follow standard procedures for crediting others' work.

Professor Churchill's lawyer, David Lane, said he believed that the inquiry was "blatantly unfair" because the professor was given no opportunity to present a defense, and that the decision to continue the inquiry was driven by politics.

"If they had bothered to call Ward Churchill, they would have investigated his response, found the allegations to be baseless, and there would have been no further action taken," Mr. Lane said.

The university was closed on Friday for spring break, and no one from Dr. DiStefano's office could be reached for comment.

The chairwoman of the Boulder Faculty Assembly, Barbara A. Bintliff, said in a telephone interview that she fully supported the chancellor's decision.

"He has a responsibility to investigate," Ms. Bintliff said. But she added that it troubled her that the impetus for the investigation began with a question of controversial speech.