CNN  — 

The parents of the teenager who killed four students in the 2021 school shooting in Oxford, Michigan, were each sentenced Tuesday to 10 to 15 years in prison, weeks after being convicted of manslaughter.

James and Jennifer Crumbley, who each had faced up to 15 years in prison, have already been imprisoned for over two years since their arrest in a Detroit warehouse days after the shooting. Though they were tried separately, their sentencing took place together in an Oakland County courtroom.

They are the first parents to be held criminally responsible for a mass school shooting committed by their child?as the nation continues to grapple with the scourge of gunfire on campus.

Before imposing her sentences, Oakland County Circuit Court Judge Cheryl Matthews told families of the victims she could never understand their pain but assured them she “saw what you saw and I heard what you heard” at both trials. The convictions, she said, were not about poor parenting.

“These convictions confirm repeated acts or lack of acts that could have halted an oncoming runaway train, about repeatedly ignoring things that make a reasonable person feel the hair on the back of their neck stand up,” the judge said.

“Opportunity knocked over and over again, louder and louder and was ignored. No one’s no one answered. And these two people should have and sure didn’t.”

Matthews said James Crumbley provided “unfettered access to a gun or guns as well as ammunition in your home,” while Jennifer Crumbley?“glorified the use and possession of these weapons.”

The Crumbleys addressed the families and the court before sentencing.

“I sit here today to express my deepest sorrows for the families of Hana, Tate, Madisyn, Justin and to all those affected on November 30, 2021,” Jennifer Crumbley said.

She said she was there “not to ask for your forgiveness, as I know it may be beyond reach, but to express my sincerest apologies for the pain that has been caused.”

“I will be in my own internal prison for the rest of my life,”?Jennifer Crumbley added.

James Crumbley said: “Before I address this court directly, I want to do something that I had never been able to do … I want to say I can’t imagine the pain and agony for the families … that have lost their children and what they’re experiencing and what they’re going through.”

He added, “I cannot express how much I wish that I had known what was going on with (Ethan) or what was going to happen, because I absolutely would have done a lot of things differently.”

Earlier Tuesday, parents of the slain students addressed the court and the defendants.

Nicole?Beausoleil, mother of Madisyn Baldwin, remembered her daughter’s laugh, her smile, her smarts and her creativity before turning her comments to the Crumbleys.

“When you knew the gun was missing, you called the police knowing it was your son who took it. I was having family call every hospital describing what (Madisyn) looked like,” Beausoleil said, growing emotional.

“When you texted ‘Ethan don’t do it,’ I was texting Madisyn, ‘I love you please call mom.’ ”

Justin Shilling’s dad, Craig, spoke of the “pain, anger, heartache, regret, anxiety, stress” he lives with every day.

Craig Shilling, father of Justin Shilling, reads a victim impact statement on Tuesday at Oakland County Circuit Court in Pontiac, Michigan.

“Literally every single aspect of my life has been affected by this tragedy,” he said, wearing a black hoodie with a photo of his smiling son.

“The blood of our children is on your hands,” he told the defendants.

Justin’s mother, Jill Soave, said the tragedy was completely preventable.

“If only they had done something, your honor, anything, to shift the course of events on November 30, then our four angels would be here today,” she said.

“It is devastating and heartbreaking that it doesn’t appear that either of you cherished or even wanted your son. But I wholeheartedly wanted and cherished mine,” she added. “You have failed your son, and you have failed us all.”

Reina St. Juliana, whose sister Hana was 14 years old when she was killed, lamented that her “10-year-old little brother had to learn how to write a eulogy for his sister before he even learned how to write essays.”

After sentencing, Oakland County Prosecuting Attorney Karen McDonald said the defendants expressed “feeling bad” but what mattered to the victims’ families most was an expression of remorse and “acknowledgement of the wrongdoing and some sort of reconciliation or apology for that – and that didn’t come.”

“These were tragic and awful, awful deaths and what these families have gone through, and it is preventable. It is preventable,” McDonald said.

In a statement, McDonald added: “Nothing will bring their children back, but the Judge recognized the suffering these defendants caused, and she acknowledged the victims and their families. The sentence today provides the highest level of accountability under the law, and that’s appropriate.”

In separate sentencing memos, prosecutors asked the judge to sentence each parent to 10 to 15 years in state prison, saying the parents showed a “chilling lack of remorse.” In particular, the prosecution noted James Crumbley made threats against McDonald in several jail calls. “There will be retribution, believe me,” he said in one, according to the memo.

But attorneys for the parents have asked for their clients to be sentenced to less than five years in prison each. In a sentencing memo dated April 5, the defense attorney for Jennifer Crumbley asked the judge to give her client credit for the 27 months she has served behind bars and allow her to be placed under house arrest “on a tether” at the defense attorney’s home, where she can be supervised.

That way, “Mrs. Crumbley would be able to work remotely and begin to rebuild her life,” but would not be out in the community, the memo says. The memo notes Jennifer Crumbley is “hugely distraught and remorseful” about the shooting and said a sentence between 29 to 57 months would be “more proportional” than what prosecutors asked for.

In a separate memo from April 5, James Crumbley’s defense attorney said his client has “expressed significant remorse” and sorrow for those affected by the killings, and asked the judge to sentence him either to 28 months in prison with credit for time served, along with a maximum period of supervision, or 43 months in prison with credit for time served.

The defense also denied that James Crumbley has threatened physical harm to the prosecuting attorney, saying he “at worst engaged in frustrated name calling.”

The sentencing represents the end of a dramatic saga that has pushed the boundaries of who is responsible for a mass shooting. Prosecutors used a?novel legal theory?in charging the parents with manslaughter even though they did not pull the trigger — the first time the parents of a school shooter have been charged with such serious crimes.

Ethan Crumbley, 15 at the time, brought a Sig Sauer 9mm firearm from home and opened fire at?Oxford High School, killing four students and wounding six others and a teacher.

His parents were arrested days afterward and accused of involuntary manslaughter for their role in the killings.

Ethan was sentenced last year to?life in prison without parole?after pleading guilty to?terrorism?causing death, four counts of murder and 19 other related charges. He?did not testify his parents’ trials, as his attorneys said he would invoke his Fifth Amendment right to silence.

What happened at the trials

From top left, Hana St. Juliana and Justin Shilling 
From bottom left, Tate Myre and Madisyn Baldwin

At their trials, prosecutors used testimony from shooting survivors, police investigators and school employees to prove that the parents were “grossly negligent” in allowing their teenage son to have access to the gun and ignoring signs of his spiraling mental health.

In particular, the testimony showed James purchased the firearm for his son on Black Friday, four days before the shooting. The next day, Jennifer took her son to the firing range for target practice. “Mom & son day testing out his new Xmas present,” she wrote afterward on social media. The parents failed to properly secure the firearm, as James Crumbley hid it in their bedroom but did not use any locking device, the prosecution argued.

In addition, the trials focused on a pivotal meeting between school employees, Ethan and his parents on the morning of the shooting. Ethan had been called into the school office after he made?disturbing writings on a math worksheet, including the phrases “blood everywhere” and “my life is useless” and drawings of a gun and bullet.

The school employees recommended the parents immediately take him out of class and get him mental health treatment, but they declined to do so, saying they had work. The Crumbleys also did not mention to the school the recent gun purchase. Afterward, Ethan was sent back to class. About two hours later, he took the gun out of his backpack and opened fire at the school.

Jennifer Crumbley took the stand in her trial and blamed her husband, the school and her son for the shooting, while expressing no regret of her own. “I’ve asked myself if I would have done anything differently, and I wouldn’t have,” she testified.

By contrast, James Crumbley did not testify in his trial, and his attorney argued he simply didn’t know about his son’s plans or mental issues.

Still, Jennifer Crumbley was convicted of four counts of involuntary manslaughter in early February, and James Crumbley was convicted of the same counts in March.

In pre-sentence investigation reports included in the prosecution’s sentencing memos, the parents continued to defend their actions.

“I am wrongly accused, and now wrongly convicted of Involuntary Manslaughter. My actions were that of any other parent,” James Crumbley wrote. He also said he “had no knowledge of what (my son) was going to do, or presented with ANY warning signs,” and he defended his gun safety efforts. “I followed the law and took gun safety to the point as needed.”

In her report, Jennifer Crumbley sought to clarify her testimony, saying she would not have done anything differently. “With the information I have now, of course my answer would be hugely different. There are so many things that I would change if I could go back in time,” she said. “I never imagined he would hurt other people in the way that he did.”

The parents’ defense attorneys have?argued the charges?have no legal justification, but appeals courts have?upheld them.

CNN’s Celina Tebor, Nicki Brown, Antoinette Radford and Maureen Chowdhury contributed to this report.