EVANSTON, Ill.  For more than a decade, classes of students at Northwestern University’s journalism school have been scrutinizing the work of prosecutors and the police. The investigations into old crimes, as part of the Medill Innocence Project, have helped lead to the release of 11 inmates, the project’s director says, and an Illinois governor once cited those wrongful convictions as he announced he was commuting the sentences of everyone on death row.

But as the Medill Innocence Project is raising concerns about another case, that of a man convicted in a murder 31 years ago, a hearing has been scheduled next month in Cook County Circuit Court on an unusual request: Local prosecutors have subpoenaed the grades, grading criteria, class syllabus, expense reports and e-mail messages of the journalism students themselves.

The prosecutors, it seems, wish to scrutinize the methods of the students this time. The university is fighting the subpoenas.

Lawyers in the Cook County state’s attorney’s office say that in their quest for justice in the old case, they need every pertinent piece of information about the students’ three-year investigation into Anthony McKinney, who was convicted of fatally shooting a security guard in 1978. Mr. McKinney’s conviction is being reviewed by a judge.