Former Rocky Ford police Officer James Ashby was convicted Thursday of second-degree murder in the 2014 slaying of a man in his mother’s kitchen, becoming the first Colorado officer to be found guilty of murder in an on-duty death in decades.

Ashby had pleaded not guilty and had been on trial for more than a week in the slaying of 27-year-old Jack Jacquez. Jurors began deliberating midday Wednesday and returned Thursday morning before handing down their findings.

In all, the Otero County jury deliberated for about 11 hours before its guilty verdict was read. Ashby, 33, is scheduled to be sentenced at 9 a.m. Sept. 23 in La Junta.

He faces up to 48 years in prison.

When he was arrested a month after Jacquez’s Oct. 12, 2014, slaying, Ashby became the first Colorado policeman in at least two decades to face a murder charge in an on-duty death. A Denver officer was acquitted in a 1992 shooting. It was not immediately clear when the last Colorado police officer was convicted of murder in on an on-duty death, or if it had ever happened.

“It’s bittersweet,” said Jacquez’s sister, Kelly Buterbaugh. “Yes, we got a guilty verdict. The jury saw all the evidence that he was in the wrong. That doesn’t mean that my brother’s still here. A guilty verdict doesn’t bring my brother back.”

Buterbaugh said she went to her brother’s grave in Rocky Ford after leaving court Thursday to tell him what happened. She said she needed some time alone with his spirit.

“Everyone is throwing around the word ‘justice,’ ” she said. “Justice would be served if my brother was still alive. To me, this was a man being held accountable for his actions.”

James Bullock, the district attorney who prosecuted the case, said justice had been done.

“This jury looked at the evidence in this case and decided this killing could not be sanctioned by reasonable people,” he said.

Bullock said the Rocky Ford community should be proud of the way the case was handled by law enforcement from the outset, all the way through the verdict.

“Make no mistake, this prosecution happens not in spite of law enforcement but because of law enforcement,” he said.

Investigators say Ashby followed Jacquez into the home of Jacquez’s mother in the early-morning hours and shot him in the back. Ashby told investigators he thought Jacquez was a burglar, court records show, but officials say he had no reason to believe Jacquez was committing a crime.

Jacquez’s mother, Viola, told The Denver Post that Ashby opened fire on her son inches from her face.

“It was one of those moments where you’re falling off a cliff,” she said in an interview after the shooting.

Investigators found Ashby fired two rounds at Jacquez, one of which severed his spine and pierced his heart and lung before lodging in his chest. A coroner’s report said he was “immediately rendered a paraplegic.”

Ashby’s other bullet sailed across Viola Jacquez’s home, including a room in which Jack Jacquez’s pregnant girlfriend was sleeping, before lodging in a wall at the other end during the 2 a.m. confrontation.

Ashby was arrested a month after the shooting and fired from the Rocky Ford police force. He said Jacquez was armed with a wooden baseball bat and that he feared for his safety when he opened fire.

The shooting sparked an outcry in Rocky Ford, a town of 4,000 about 50 miles east of Pueblo. Protesters cited parallels to the police killings of Michael Brown in Ferguson, Mo., and Eric Garner in New York.

The Colorado Bureau of Investigation, in its review of the shooting, said Ashby lied about circumstances that led up to and followed the shooting, finding that many of his statements contradicted physical evidence and witness accounts.

Specifically, investigators found Ashby’s version of the shooting differed from that of a man who was riding with him during his 7 p.m.-to-5 a.m. shift the morning of the encounter.

At least four of Rocky Ford’s 10 officers have had problems in previous law-enforcement jobs or had criminal convictions that might have kept them from being hired at bigger departments or in other states, a Post analysis found.

Rocky Ford’s former police chief told The Post that Ashby’s records from his previous law enforcement job in Walsenburg, where he had been the subject of several internal affairs investigations, were not reviewed before he was hired. Officials instead relied on verbal recommendations from his former supervisors.

Eight days before shooting Jacquez, Ashby tackled a suspect over a holding cell bench, court documents show. He was found to have violated department policies in that encounter.

“Given Officer Ashby’s well-known history of perpetrating police abuse and misconduct, he never should have been entrusted with a badge and a gun,” said a statement from the Jacquez family released by their Denver lawyer, Qusair Mohamedbhai. “The jury’s verdict is a stain on the entire Rocky Ford Police Department. We will continue to seek justice and demand answers from the city of Rocky Ford as to why Officer Ashby was ever in a position to commit this heinous crime.”

Mohamedbhai is a civil rights attorney who often represents victims of alleged law enforcement abuse in lawsuits.

Jack Jacquez Sr., Jacquez’s father, said Ashby appeared nervous before the verdict was read, a change from the cocky confidence he saw in his son’s killer over the past several months. He was planning Thursday night to burn all the documents he amassed in the case as a way of getting the stress from the court proceedings off his chest.

“It was a weight off of our hearts that our son didn’t die in vain,” he said. “We’re just really happy.”