Carnell, 23, will spend between 15 and 25 years in prison for a string of attacks that took place one day last August in Meridian.
After three hours of testimony Wednesday morning, Fourth District Ada County Judge Richard Greenwood took 90 minutes over the lunch break to craft a sentence that took into account the damage that Carnell inflicted while allowing him to become rehabilitated and be released with the hope he becomes a productive citizen.
Greenwood said Carnell was under a "drug-induced psychotic episode" when he seriously injured two men and inflicted lesser injuries on three others and a dog during a series of nine events that took place over a two-hour period Aug. 21 in Meridian.
Mike Rice, a construction contractor, and Chris Cade, a Nampa fire captain who was riding his bicycle on his day off, each spent several days at Saint Alphonsus Regional Medical Center after they were attacked. Rice was struck numerous times in the head and back with a shovel, while Cade was struck in the head with a skateboard as he rode at an estimated 15 to 20 mph down a bicycle path.
"The victims have suffered debilitating injuries for no apparent reason," Greenwood said as he announced his sentence.
Carnell pleaded guilty in April to robbery, aggravated assault, aggravated battery, battery with intent to commit a serious felony and first-degree arson.
Prosecutor Shelley Akamatsu asked Greenwood to sentence Carnell to between 30 years and life in prison. She said he deserved a stiff sentence for attacking Rice and Cade, who are still dealing with their injuries almost 11 months later.
She said he also needed to be punished for setting fire to his apartment, causing $75,000 in damage, for pummeling a woman who complained about his drug use in their neighborhood and for punching a 15-year-old boy in the face and stealing his skateboard, an attack captured on a skate park videotape that was played in court Wednesday.
"He had no human empathy toward any of his victims," Akamatsu said.
Defense attorney Eric Rolfsen asked for a five-year sentence and supervision for another 15 to 20 years.
"He knows he deserves severe punishment. There has never been any question of that," Rolfsen said.
Greenwood's sentence settled in-between the two suggestions.
"It's a lot less than we recommended," said Akamatsu, who noted Carnell could be out of prison by the time he's 38 or as late as 48.
"After that, there will be no supervision," Akamatsu said.
Rolfsen declined to comment outside court, as did Cade and Michael and Mary Carnell, Sean Carnell's parents. Rice, who had been in the courtroom earlier in the day, did not return for the sentencing.
"I feel for him but I don't think 15 years is long enough, said victim Robert Stapish, who was tipped over in his wheelchair by Carnell.
Carnell, who was secured by handcuffs and a belly chain, sat motionless as Greenwood announced the sentence.
As deputies led him out of the courtroom, he turned and mouthed "I love you" to his parents.
In two letters sent last fall to the Idaho Statesman, Carnell said he was under the influence of a combination of "bath salts" and methamphetamine when he went on his rampage. Bath salts are a powerful drug that causes paranoia, agitation and hallucinations, along with violent behavior. He told the newspaper he believed at the time he had only ingested meth.
Im deeply sorry and ashamed for what happened to these victims, Carnell wrote from jail last November. I cannot change what happened to them; I wish I could.
At the time, he wrote that he expected he might have to serve 20 years in prison.
"This is just a terrible case in all regards," Rolfsen said in court Wednesday. "He very much took responsibility for his horrible actions."
Carnell briefly addressed Greenwood, saying he wanted to apologize to his victims for the harm he caused them.
"I'm sorry," he said.
Earlier, Rice, 59, testified that he still suffers daily pain from being struck numerous times in the face and back with a shovel Carnell picked up at a construction site where Rice was working.
He broke a cheekbone and three ribs in the attack. His left ear was also damaged.
"Basically, it was lights out for me," Rice said. "I didn't see anything, didn't hear anything. There was no warning. The next thing I remember I was in an ambulance."
He said it was hard to "drink, sneeze, eat, drink and sleep" during the four days he spent in Saint Alphonsus Regional Medical Center and for weeks afterward. His ribs still give him trouble, said Rice, who before the attack was a motorcycle enthusiast and skier.
"They're still not healed," Rice said. "They're still painful."
Cade, 37, who lives in Meridian, was headed on a 50-mile bike ride when he was struck in the face with a skateboard wielded by Carnell.
The impact cracked Cade's bicycle helmet and sent him sprawling on the ground. He suffered three fractures across his face, multiple fractures of his nose, a half-dollar-sized gouge in his left shoulder, a broken shoulder blade and broken collar bone. He also suffered from a collapsed lung and a broken rib. He also lost four front teeth.
"I have no memory of anything on that path," said Cade, who first became aware something bad had happened when he woke up at Saint Al's.
Cade, a captain with the Nampa Fire Department, spent five days in the hospital. He could not swallow and had trouble breathing even after he left the hospital.
Carnell, who was adopted by Michael and Mary Carnell when he was eight months old, was described as a good child who excelled at soccer and later at football while he was growing up.
That changed before his junior year at Capital High School when he was seriously injured in a pickup wreck after he and some friends played a summer pickup game of football. A friend wrecked the pickup and Carnell, who was riding in the back, had his head crushed under the pickup after it rolled.
He began abusing alcohol and drugs and dropped out of school before the end of his junior year. His parents asked him to leave home after he turned 18, because they didn't want him to negatively influence their younger children.
"We lost our son. He became an addict and made terrible choices," Michael Carnell said.
Mary Carnell said she and her husband were heartbroken over the injuries caused by their son's actions. It was especially troubling because of the injuries he had suffered in the wreck and knew what it was like to have a long recovery.
"I want to say my wife and I are sorry that our son was involving in something that injured so many people," Michael Carnell said, looking out toward Rice and Cade.