Mr. Protess, who taught at the Medill journalism school at Northwestern University, was the founder and driving force behind the Medill Innocence Project, which was instrumental in exonerating at least 12 wrongly convicted defendants and freeing them from prison, including five who were on death row in Illinois, and in prompting then-governor George Ryan to clear the rest of death row in 2003.

But during an investigation into a questionable conviction, the Cook County state’s attorney turned her attention instead on Mr. Protess and his students. Since then, questions have been raised about deceptive tactics used by the Medill students, about allegations that Mr. Protess cooperated with the defense lawyers (which would negate a journalist’s legal privilege to resist subpoenas) and, most damning, whether he altered an e-mail to cover up that cooperation.