Prosecutors in Chicago are claiming that Northwestern University journalism students paid off a witness in an effort to prove a man was wrongly convicted.

The allegation came in a Cook County criminal court murder case Tuesday.

Students contend prosecutors have put the wrong man behind bars for a 1978 murder. But prosecutors say students were motivated to find evidence of Anthony McKinney's innocence to get better grades. Prosecutors have subpoenaed the students' grades.

Prosecutors claim the students paid $60 to a man who said he was present at the murder and that McKinney was not.

Journalism professor David Protess denies the allegations. He claims it's part of a "smear campaign" by the Cook County state's attorney's office.