AUGUSTA — A Clinton man pleaded guilty Thursday to murdering a man in a Waterville shooting in 2024.

Richard Hatt, 54, who was scheduled to go on trial in July, admitted during a hearing at the Capital Judicial Center that he killed Stephen Killam, 47, of Fairfield, with a 9 mm handgun Oct. 15, 2024.

Hatt said he mistakenly suspected Killam of having a relationship with Hatt’s on-and-off girlfriend.

A handful of people attended the hearing and sat on the prosecution’s side of the court room. No supporters appeared to be in court for Hatt.

The prosecutor, Assistant Attorney General Jen Ackerman, described Hatt’s actions on Oct. 15, 2024, and the evidence the state would have presented in a trial.

About an hour before the shooting, Ackerman said, evidence showed that Hatt invaded a home on Winter Street in Waterville and threatened and assaulted a man he believed to be Killam.

Hatt was also charged with criminally threatening that man’s girlfriend with a dangerous weapon. Hatt pleaded no contest.

Ackerman said Hatt later told detectives that when he realized he had the wrong man and would likely go to jail, he went in search of Killam and decided to kill him. Hatt found Killam at Mount Joseph at Waterville, a rehabilitation and nursing center where Killam and his girlfriend worked.

The shooting occurred while Killam was in his car with his girlfriend. An autopsy determined that Killam died of multiple gunshot wounds; he was shot 13 times. Killam’s car had several bullet holes in the windshield on the driver side.

Killam and his girlfriend had temporary protection orders against Hatt, Ackerman said. Killam had obatain his order on Oct. 10, and it was served Oct. 12, three days before the fatal shooting.

Following his arrest, Ackerman said, Hatt spoke with detectives and admitted his involvement in the shooting. He said he saw Killam slumped over in the driver seat of his car as he was shooting, but said, “I’ll admit I dumped the rest of them out of spite and hate.”

Hatt is being treated for a medical condition that Justice Michaela Murphy said “looms large in the negotiations that took place.” She requested more information following the hearing.

The murder charge carried a maximum sentence of up to life in prison without the possibility of parole, but the plea deal between the defense and prosecution capped the maximum sentence at 45 years. Ackerman said the prosecution would seek the maximum sentence, but she expected the defense to seek leniency.

Hatt also pleaded guilty to one count of aggravated assault with a dangerous weapon, one count of criminal threatening with a dangerous weapon, one count of burglary Class A and one count of possession of a firearm by a prohibited person.

Hatt’s attorney, Mitchel Roberge, said he believed the guilty pleas were in his client’s best interest.

After asking Hatt a series of questions Tuesday, Murphy said she was satisfied that Hatt entered his plea knowingly and intelligently, with full understanding of the nature of the charges and the consequences.

A sentencing date will be scheduled.