SYCAMORE – No eyewitnesses, no murder weapon, no time of death and no cause of death meant no sure-fire conviction as far as DeKalb County State’s Attorney Richard Schmack was concerned.

An hour after William “Billy” Curl accepted a plea agreement that will keep him in prison until 2047 for the murder and rape of Northern Illinois University freshman Antinette “Toni” Keller, Schmack defended his criticized decision to pass on a trial that could have resulted in a 60-year sentence.

“[Prosecutors] also had to consider the gross injustice of a potential verdict of not guilty and the unimaginable pain that would have meant for [Keller’s] loved ones,” Schmack said. “Some may be able to put that risk out of their thoughts, but prosecutors cannot.”

Schmack pointed to high-profile, televised murder trials involving O.J. Simpson and Casey Anthony that resulted in surprising not-guilty verdicts. As state’s attorney, he said it was his first responsibility to protect the public from the future criminal threat Curl posed.

“Some of those cases would appear to be stronger than ours,” Schmack said. “The outcome was not assured.”

The man who indicted Curl disagreed.

Former DeKalb County State’s Attorney Clay Campbell attended Wednesday’s sentencing and said it was a sad end to an event that demanded greater justice. Campbell, who became State's Attorney in December 2010 shortly after Curl was charged, said he was sorry he could not complete his commitment to the Keller family and noted their absence Wednesday was likely a sign of how they felt about the agreement.

From bone fragments that tested positive for Keller’s DNA to the scratches on Curl’s chest, his multiple accounts of events and his attempt to flee to Mexico and Louisiana, Campbell said the evidence and timeline would have held up at trial.

“It very likely would have been the longest trial in DeKalb County history,” he said. “I was 100 percent confident in the evidence.”

Campbell said it is just as important for the state’s attorney to pursue justice to the maximum extent of the law for victims as it is to protect the public.

Keller’s family and supporters were not the only ones displeased with the agreement.

Wednesday’s sentencing started with a plea from Moria Curl to her brother as she shouted for him to turn down the deal and fight for his freedom.

“They’re railroading you!” she shouted to her brother as she was escorted from the courtroom.

The reaction came as somewhat of a surprise to DeKalb County Public Defender Tom McCulloch, who said his client was at peace with his decision Wednesday morning. McCulloch said Curl maintains his innocence in an Alford plea while having a chance at life outside of prison with his scheduled release date to come when he is 71 years old.

In an Alford plea, the defendant maintains innocence but admits the evidence could convince a judge or a jury to find him guilty.

“I think people make their own decisions when it comes time to fish or cut bait,” McCulloch said, adding he encouraged Curl to keep an open mind about a deal. “Everyone is looking for a guarantee in this world.”

Curl must serve all of his 37-year sentence. He has been credited with almost 2 1/2 years of time served since his October 2010 arrest.

Keller, an NIU student from Plainfield, was last seen Oct. 14, 2010, when she told friends she was going for a walk in Prairie Park. Her burned body was found in the park two days later. She was 18.

NIU spokesman Paul Palian said the Huskie community, which established scholarships in her honor and developed memorials, hopes Wednesday’s sentencing can bring some healing to the Keller family.

“Our thoughts and prayers have been and continue to be with the Keller family,” he said. “Our hopes are that today’s events will be another step in the healing process for them.”

Editor's note: This article has been corrected to reflect that Clay Campbell was DeKalb County State's Attorney when Curl was indicted, but not when he was charged.