DENVER - An expert on academic freedom said Tuesday the University of Colorado should be held to a high standard of proof if it tries to punish an embattled professor on allegations of plagiarism.A faculty committee is investigating research misconduct charges against Ward Churchill, a tenured professor of ethnic studies who first came under fire for likening Sept. 11 victims to an infamous Nazi."The burden of proof should be a very high standard," said Jonathan Knight, director of academic freedom and tenure programs for the American Association of University Professors.Churchill has confirmed that a subcommittee of the university's Standing Committee on Research Misconduct has recommended that the full panel press ahead with its inquiry into seven plagiarism allegations against him.But the subcommittee recommended dropping an investigation into allegations that Churchill falsely claimed to be an American Indian to give his research more credibility. The subcommittee also advised dropping the inquiry into a charge of copyright infringement.Churchill has denied the allegations.He came under fire this year over an essay comparing some World Trade Center victims to Adolf Eichmann, who helped orchestrate the Holocaust. The essay was written shortly after the Sept. 11 attacks but attracted little attention until this year, after Churchill was invited to speak at a small college in New York state.He has refused to retract the statement but said he wishes he had phrased it differently.In March, CU leaders decided Churchill couldn't be fired over the essay because of First Amendment protections, but they ordered the review of allegations of plagiarism and false claims of Indian background.CU spokeswoman Pauline Hale said school officials could not comment until the faculty committee makes a final decision, which could come before the end of the month.Knight said his group does not track the number of plagiarism investigations on college campuses, partly because many remain confidential. But he said Churchill's case is unusual in the amount of national attention it has attracted."I hope the burden (of proof) is as I have described it, and is not influenced in one way or another by any surrounding events," he said.The preliminary investigation into Churchill's ethnicity was nearly unprecedented, Knight said.Churchill said he believes someone connected with the university has leaked details of his case to the media. He and his attorney, David Lane, both said they did not discuss the subcommittee's recommendations until they were contacted by reporters who already knew about them."Who is doing the leaking? I couldn't say," Churchill said. "It's conceivable it was unintentional."Hale said she had not heard of anyone from the university sharing the information, which would be a violation of campus policy."I'm a little bit puzzled by all of that," she said.Lane said he was evaluating whether to file a suit in federal court over the university's delay in deciding on Churchill's request for a sabbatical next year to write a book on the Black Panther Party.University officials have said they won't decide on the sabbatical until they hear the outcome of the plagiarism and research misconduct evaluations.Lane said the move was retribution by the university for Churchill's comments.