Before Benjamin Koller was sentenced Wednesday to 40 years in prison for committing the abuse that led to his infant son’s death, he wept during a slide show of the 4-month-old boy’s short life.

First flashed pictures of friends and family members cradling the healthy boy named Jack. Then came shots of Jack hooked up to monitors after his father shook, bit and suffocated him. Those photos were followed by heartbreaking images of the child’s final hours and a picture of him in a gray stocking hat with his eyes closed and his arms crossed.

The slide show ended with a shot of Jack’s headstone, which was marked with a Superman logo symbolizing the weeks that he lived beyond what doctors thought was possible.

“I don’t know why this tragedy happened — I don’t know why I did what I did,” Koller, 27, told a packed courtroom at his sentencing hearing Wednesday. “I don’t have the answers, and I can assure you that I’m just as confused of the whys as all the rest of us. What I do know is that I’m so terribly, terribly sorry for the mistakes I made that cost our baby boy Jack, our Superman, his life.

“I’m sorry, Jack, for not being a better father,” Koller said, drying his eyes.

Koller, who originally faced a first-degree murder charge, pleaded guilty in May to a lesser charge of child abuse resulting in death, punishable by 16 to 48 years in prison. His public defender asked Boulder County District Court Judge Maria Berkenkotter to sentence him to between 26 and 32 years in prison.

Ryan Brackley, first assistant to the district attorney, asked for the maximum 48-year penalty.

Berkenkotter sentenced Koller to 40 years followed by five years of parole based on aggravating factors, such as the repeated abuse and the fact that Koller delayed Jack’s ability to get help by keeping the truth to himself. She said she didn’t give him the maximum based on mitigating factors, such as the fact that he had to overcome abuse he suffered as a child and the resulting mental health issues.

Koller was arrested last July after he and his common-law wife, Jennifer Schmidt, brought Jack — who was just 7 weeks old at the time — to the hospital with critical injuries. Jack had a skull fracture, bruising, bite marks and scratches to his face. Doctors determined that Jack had widespread brain damage, and his father was arrested.

The infant was released from the hospital in August into the care of his grandmother, but Jack died of his injuries on Oct. 5.

Koller told the courtroom Wednesday that his “life was complete” when his son was born, and his first moments holding the infant were the “proudest, happiest days of the rest of my life.”

“Then, all of a sudden, without warning, my son was lying in a hospital fighting for his life,” Koller said.

After being arrested, Koller said he called his mom daily to get updates on how Jack was doing.

“I have lived in hell and breathed hell,” he said. “And I will continue to live and breathe that hell for the rest of my life.”

Koller admitted to making “unintended” mistakes that killed his son but said it took time for him to get to a place of acceptance.

“What father wants to admit to shaking and biting and putting their hand over their child’s mouth?” he said. “But I have admitted to those things and accepted responsibility.”

Schmidt, Koller’s common-law wife and Jack’s mother, wasn’t charged in her son’s death and told the courtroom Wednesday about the hopes and dreams she had for her little boy. She imagined him as a rock star, a U.S. president, a Calvin Klein model.

“I wanted to watch sunsets, wish upon stars and build sandcastles,” she said. “I wanted him to grow to love and be loved. Nothing I can say or do will bring Jack back. He is dead, and all those dreams left with him.”

Schmidt described the roller-coaster of emotions she went through carrying her son, seeing him healthy and strong when he was born, watching him get sick and yearning to hold him when he was hooked up to machines.

“The only thing I wanted was to hold him and tell him how much I loved him,” she said. “But I couldn’t even touch his baby-soft skin. I watched my life crumble before my eyes.”

Schmidt said she and her family made the decision to let Jack die rather than put him through more surgeries that would have kept him alive as a “vegetable” at best. During his last days, they did their best to make him comfortable, she said.

“We read stories to him and sang to him and gave him sweet kisses,” she said. “We sat on the porch and watched the sunset. We tucked him in at night.”

When she buried him, Schmidt said, she played a lullaby and read him “Good Night Moon.”

“It felt like my life was worthless,” she said. “Everything I loved was gone.”

Schmidt’s mother, Claudia Riggs, told the court that she worries she has lost her daughter along with her grandson.

“I wonder if I will ever have another grandchild because of the damage my daughter has suffered,” she said. “Will she ever be happy again?”

Schmidt’s father, Mark Schmidt, said the result of Koller’s actions is too great to let him off without significant prison time.

“He had no regard for Jack’s life, and today I have no regard for his,” he said.

But Koller’s mother, Valerie Koller, said her family is going through the same pain that Schmidt’s is going through, and she talked about her son’s desire to do something good in this world.

“Ben talked to me about becoming a dad and said he wanted to be the best dad he could,” she said, adding that she believes he never meant to hurt his son. “He has asked me to forgive him, and I do.”