For more than two months, Judge David Johnson said he had been losing sleep over the case that returned to his courtroom Thursday.

Calling it the toughest decision he’s faced in 12 years on the bench, Johnson struggled with the fate of Karla Jean Winterfeld, the Duluth middle school teacher who admitted to sexually assaulting a 15-year-old former student.

After an emotional two-hour hearing, however, the judge was unequivocal in his delivering his sentence. Winterfeld, he said, would get the 12-year prison term requested by a prosecutor.

“He had hope for a better life and you, through your actions, destroyed that,” Johnson told the defendant. “You destroyed his life. I can’t get past that. I simply can’t.”

Winterfeld, standing to receive the sentence, dropped her head as the judge denied her request for leniency. Crying, she held a tissue as she placed her hands behind her back to be handcuffed by security personnel as a packed gallery looked on.

Winterfeld, 34, pleaded guilty in October to a felony count of first-degree criminal sexual conduct, admitting that she had engaged in multiple sexual acts with the victim over the course of several weeks in May.

The fact that the judge had such wide discretion - ranging from probation to the guideline 12-year prison term - was a result of Winterfeld admitting guilt without the benefit of any plea agreement.

The courtroom, which holds about 50 spectators, did not come close to accommodating the number of people who gathered in the hallway beforehand hoping to get a seat. Many were left outside to await the news.

The victim has been left to deal with lifelong trauma stemming from Winterfeld’s actions, his uncle told the judge.

“I can see it in his face, his eyes, his actions,” said the uncle, who serves as his guardian. “He’s starting to bottle up. He won’t talk to me. All the effects are starting to show.”

He added: “It hurts. It shouldn’t have happened. You should’ve known better. You say this is far from over. Well, I’ve got to deal with this for the next few decades.”

Winterfeld, who formally resigned in August after 11 years with the Duluth school district, read a brief statement, calling her behavior “inexcusable” and echoing comments from a written letter she previously submitted to the court.

“I will never forgive myself for what happened,” she said. “I will live with this guilt for the rest of my life.”

Defense attorney Jacob Brodin called two witnesses to testify in support of his motion for probation.

Jessica Metzger, a therapist at the Duluth Institute, a mental health clinic, said Winterfeld voluntarily entered treatment and has been “fully accountable” for her crimes.

“She has been very motivated, very engaged, very interested in learning why she did what she did,” Metzger testified, adding: “I don’t believe she poses any risk to public safety.”

Gerald Henkel-Johnson, a psychologist who completed a psychosexual evaluation, said it was clear Winterfeld had experienced a “history of significant trauma” as a child. He opined that she has been honest and accountable for her actions and said female sex offenders, while rare, have a very low rate of recidivism.

Peter Rainville, another defense attorney, said the testimony demonstrates that Winterfeld has been “working extremely hard to fix the broken part of her that caused this offense.”

“She is just plain amenable to probation,” Rainville argued.

St. Louis County prosecutor Jon Holets, on the other hand, said the substantial prison sentence would serve as a guard against bias in the court system. Noting most defendants do not have the means or connections to hire expert witnesses and solicit dozens of letters of support, Holets said the court should be blind to Winterfeld’s race, sex and socioeconomic status.

“There is nothing particularly different or special about this case except that the courtroom happens to be filled,” the prosecutor said. “This is exactly what sexual assault and sexual abuse look like.”

Holets said Winterfeld engaged in grooming behavior before the first incident. He added that police recovered photographs and recordings depicting the acts, as well as evidence that Winterfeld had researched consent laws.

“She is not the victim,” Holets said.

Johnson adjourned court for a half-hour, taking a final opportunity to review all the material before rendering his decision.

When he came back, the judge was swift and blunt.

“We’re here for sentencing related to your rape of an underage child,” he said. “That’s the charge, and that’s what you’ve pled guilty to.”

The judge said that while it was clear Winterfeld needs treatment, he couldn’t look past the vulnerability of the victim. “I cannot find substantial and compelling reasons to depart,” he said.

Winterfeld must serve at least two-thirds of term, or eight years, before she is eligible for release from prison. She also will need to register as a predatory offender and be subject to 10 years of conditional release.