Monaghan receives maximum sentence for death of Paul Costello
He was sentenced Wednesday morning.
"He had all the earmarks of being a serial killer, except he got caught on the first one," Prosecutor Nelson Chipman said.
The prosecution said they didn't believe Monaghan was truly remorseful because Facebook pictures showed him partying after the murder.
Chipman says he never explained why he killed Costello.
"There's no explanation. There wasn't anything. You know the base motives we often see - revenge, anger, greed, money. There's nothing," Chipman said. "You could tell in the courtroom, there was just no emotion. It was just flat out cold blooded."
Costello's body was found inside a plastic drum on his property on November 5, 2016. His hands and feet had been tied. He suffered multiple skull and facial fractures.
The judge said because Monaghan is at a high risk for reoffending, she gave him the maximum sentence.
"Judge Bowen referred to that risk assessment, that there's a high likelihood, by using that tool, there's a high likelihood Mr Monaghan would reoffend. And that weighed heavily with the judge," Chipman said.
The state said Costello did nothing wrong. He gave Monaghan a place to live when he had nowhere else to go. He paid for the generosity with his life.
Monaghan pleaded guilty on November 6, 2017. As part of the plea deal, the second charge against him, for the theft of Costello's vehicle, was dismissed.
Monaghan was 18 at the time of the murder.
The other man charged in this case, Maeson Coffin, is scheduled for trial in 2018. He was 19 at the time of the murder.
On November 5, 2016, family members who hadn't heard from Costello for about two weeks went to his home to look for him. They found his body in the plastic drum in an outbuilding on his property.
During the investigation, the Marshall County Sheriff's Department discovered Costello's vehicle was missing. They pinged his phone and its last location was Watertown, New York.
The following day, a witness told the sheriff's department Monaghan took Costello's Buick Lacrosse to his mother's house in Watertown, New York.
Deputies learned Monaghan and Coffin had been leasing a residence from Costello. He had gone to their home on October 27 to collect rent because they had not been paying, reports said.
Monaghan had allegedly said he should kill Costello and steal his car, reports said.
Monaghan was apprehended while operating Costello's vehicle in Watertown. A woman he was with told Watertown Police Monaghan said Coffin killed the "guy" and Monaghan helped get rid of the body, according to the probable cause affidavit.
Monaghan and Maeson Lee Coffin were both charged with one count of murder and one count of auto theft.