A Press-Gazette Media report says 55-year-old Charles Mlados was convicted Monday of perjury and party to first-degree reckless endangerment.
Mlados says he didn't commit the crime but only agreed to a deal because he didn't think he'd get a fair trial. He was sentenced to 42 months in prison.
He was charged in the 1998 death of 19-year-old Chad McLean, whose body was found in a river.
Another man, Peter Hanson, was convicted of shooting and killing McLean after a night of drinking. Mlados says his only crime was remaining loyal to his co-defendant, taking him at his word that he didn't kill McLean.
Hanson is serving a life term.