DeKALB — DeKalb Circuit Judge Robbin Stuckert ruled Friday that William Curl, the man convicted of killing an NIU student in 2010, is not allowed to withdraw his guilty plea.

Curl, 41, of DeKalb, pled guilty to the murder of then NIU freshman Antinette Keller in April 2013. Keller’s burned remains were found in DeKalb Park in October 2010, along with several of her possessions and Curl’s glasses.

Curl and his attorney Daniel Transier have been trying to appeal his sentence since July 2013.

Stuckert’s decision Friday was announced in front of members of the Keller family and law enforcement officers, but not Curl, who must now serve his entire 37-year prison sentence without parole.

Transier said Curl’s previous defense lawyer Thomas McCullouch’s judgment “became affected by the case’s high profile status” and McCullouch “abandoned the investigation of [Curl’s] alibi defense” by accepting a plea deal, according to court documents. Curl’s alibi defense, or proof of being in a different location at the time of the crime, came in the form of a “collection of DVDs” put together by Curl’s assistant attorney Regina Harris. The DVDs are said to include statements from Curl and other witnesses.

Several interviews of Curl were played on Sept. 6 and 7 in court as part of the appeal process. Curl testified Sept. 7.

In Stuckert’s ruling, however, she asserted Curl failed to identify his alibi defense with his attorney during the earlier trial.

“Defendant is clearly the source of alibi defense and did not testify to any alibi defense or explain what he informed his attorney about the existence of his alibi defense,” according to Stuckert’s 11-page ruling.

Transier also said McCullouch “failed to investigate” other potential suspects, according to court documents.

Court documents also show Curl claimed State Attorney Richard Schmack “threatened to prosecute” Curl’s son if he did not enter a plea deal. At the time of the plea bargaining, Curl’s son was 13 years old.

Stuckert recounted a meeting between Curl and his defense team, which at the time was aware of the magnitude of the plea bargain.

“While he wanted to take the offer, he did not want to say ‘I’m guilty,’ ” Stuckert said in the ruling. “That was how the ‘Alford’ plea was decided upon.”

An Alford plea is a guilty plea where the defendant in a criminal case doesn’t admit to criminal act and asserts innocence, named after the 1970 Supreme Court case “North Carolina v. Alford.”

McCullouch also testified Sept. 8 that Curl was fully aware of the terms of the agreement and that he entered the plea voluntarily.

Curl had previously been diagnosed for bipolar disorder, post-traumatic stress disorder and borderline personality disorder, according to Sept. 6 testimony by clinical psychologist Jayne Braden.

It is also mentioned in appeal documents from Transier that Curl was not properly medicated to treat a mental illness during his initial interrogation, which was conducted by law enforcement in Louisiana, as Curl fled from DeKalb to Mexico following initial interviews. This was also discredited by a failure of Curl to communicate these issues.

Transier declined comment. Other representatives at the Law Office of Daniel Transier did not respond to request for comment.