SYCAMORE, Ill. (AP) — A man serving a decades-long prison sentence in the 2010 death of a Northern Illinois University student is continuing an appeal of his conviction.

Chief Judge Robbin Stuckert on Monday partially denied a motion by the state to dismiss the appeal of William Curl of conviction in the death of 18-year-old freshman Antinette “Toni” Keller of Plainfield. Her burned body was found in a park two days after she disappeared.

In May 2015, Curl filed a petition for post-conviction relief, saying he only agreed to plead guilty because his court-appointed attorney made mistakes. He also claims he entered the plea because then-DeKalb County State’s Attorney Richard Schmack threatened to prosecute the 40-year-old Curl’s 13-year-old son in connection with Keller’s murder.

Stuckert on Monday set a May 23 hearing during which a date for an evidentiary hearing may be determined.