A Colorado man was sentenced to life in prison without the possibility of parole on Monday for beating his fiancee to death and burning her remains, concluding a grim murder case that seized national attention after the woman disappeared nearly a year go.

Patrick Frazee was also sentenced to an additional 156 years in prison on other charges in the killing of Kelsey Berreth after a jury in Teller County, Colo., found him guilty of first-degree murder, solicitation to commit murder and tampering with a body. Jurors deliberated for less than four hours before reaching their verdict, according to local news media.

Frazee, 33, stood silently as Judge Scott Sells explained the sentence, NBC affiliate KOAA reported.

“Your actions were vicious, senseless, without reason or explanation,” Sells told him. “Kelsey Berreth was a wonderful mother, beloved daughter. Your crimes deserve absolute max punishment and I intend to do that.”

The verdict came at the end of a closely watched three-week trial, where days of dramatic testimony highlighted the particularly gruesome case of intimate-partner violence.

“This was totally senseless and it will haunt us — on the prosecution team and I think in this community — forever,” Dan May, Colorado’s 4th Judicial District attorney, said at a news conference after the verdict was announced.

Berreth, a 29-year-old flight instructor, disappeared on Thanksgiving last year after shopping for groceries with the couple’s 1-year-old daughter. Frazee told investigators that the couple had met up to exchange the baby.

Three days after she vanished, texts were still being sent from her phone to her fiance and her employer saying she would not be coming to work, according to police, who said at one point her phone pinged near Gooding, Idaho, about 800 miles away. Relatives reported her missing in early December, saying it was unlike her to run away without telling anyone. Her body was never found.

Frazee was arrested on suspicion of first-degree murder and solicitation to commit murder in late December. Authorities said that after interviewing numerous people they had gathered enough evidence to swear out a warrant.

Prosecutors said Frazee bludgeoned Berreth with a baseball bat at her townhouse, then took her body to his ranch and burned her remains. They did not identify a motive for the killing. In a wrongful-death lawsuit, Berreth’s parents said Frazee was seeking full custody of the couple’s daughter, according to the Associated Press.

Scant physical evidence forced the prosecution to rely on the testimony of Frazee’s longtime acquaintance, and on-again-off-again romantic partner, Krystal Lee. The two were engaged in an affair when Frazee called Lee last Thanksgiving and told her she had “a mess to clean up,” she told the court.

Lee, a former nurse in Idaho, made the 12-hour drive to Woodland Park, a small city south of Denver, where she said she spent hours cleaning up Berreth’s blood, the Colorado Springs Gazette reported. She said she helped Frazee burn his fiancee’s remains and dispose of bloodstained evidence, including stuffed animals and children’s toys.

Frazee and Berreth’s daughter was at home when the mother was blindfolded and beaten to death, Lee testified.

In Lee’s telling, it was at least the fourth time Frazee had sought to implicate her in violence toward Berreth. Before the Thanksgiving call, Frazee had thrice asked Lee to kill Berreth, the AP reported. Once, Frazee instructed Lee to slip a poisonous cocktail into Berreth’s coffee, Lee said. On two other occasions, Frazee gave Lee a metal rod and a baseball bat to bludgeon Berreth. Each time, Lee said, she didn’t go through with it. But later, she said, Frazee did.

After the two cleaned up the scene, Lee said Frazee asked her to take Berreth’s cellphone with her back to Idaho to throw off investigators searching for the missing woman.

Lee struck a deal with prosecutors, and in exchange for helping them make their case, she agreed to plead guilty to tampering with evidence. She faces up to three years in prison. In his remarks at the end of the trial, May acknowledged that he wasn’t happy with the bargain but said it was crucial to the trial.

“We did a deal with the devil,” May said. “There’s no ifs, ands or buts about that, and I’m not proud of that. But there is no question that Kelsey wouldn’t have had the sure justice today without making that deal with the devil.”

Frazee’s attorneys said the plea deal called into question Lee’s honesty, the AP reported, because the woman initially told authorities she didn’t know who Berreth was. Frazee declined to testify, and his lawyers didn’t call any of their own witnesses.

Defense attorneys also challenged the timeline of the slaying presented by prosecutors, saying the evidence against Frazee was circumstantial. “It is okay to make mistakes, but you cannot build an entire case on it and refuse to acknowledge it,” said Frazee’s attorney, Adam Steigerwald, according to the Gazette. “And that is what has happened in this case.”

Before the judge handed down the sentence, Berreth’s uncle, Scott Morin, read letters from family and friends, who described the woman as a quiet, kind and caring person.

“She was our daughter, a devoted loving mother, a sister, a friend,” wrote Berreth’s mother, Cheryl Berreth, according to the Denver Channel.

The mother’s letter also excoriated Frazee, saying he had tortured her daughter to death and left her child to “call out for mama in the middle of the night,” according to the Gazette.

“He not only killed our daughter — his child’s mother — but he chose a horrible death for her,” the letter read.

At the post-trial news conference, reporters asked Gregg Slater, an agent at the Colorado Bureau of Investigation, whether his agency would continue its search for Berreth’s remains. Standing a few feet away from the microphone, his voice faint, Slater replied, “We’ll always look for Kelsey.”

Another reporter asked Slater whether he thinks he’ll find her.

“I don’t know,” he replied. “I hope so.”