A Bountiful man pleaded guilty in 2nd District Court Tuesday to one slaying and will plead guilty to two other shooting deaths in Salt Lake County, his defense attorney says.

Russell M. Anderson, 34, pleaded guilty but mentally ill in the Aug. 29 shooting death and robbery of Frank R. Boulton in Bountiful. Anderson, 2122 S. Orchard Drive, faces murder charges in the shooting deaths a month earlier of a Salt Lake couple, Norman B. and Janet Marie Armstrong.Anderson's Salt Lake defense attorney, James Valdez, told Judge Rodney S. Page on Tuesday that Anderson will also plead guilty but mentally ill to reduced second-degree murder charges in a plea negotiation in 3rd District Court.

Carvel Harward, the prosecutor in the Davis case, emphasized that no plea bargain was struck in his case and Anderson pleaded guilty as charged.

Anderson admitted in an affidavit signed Tuesday that he gave Boulton a ride the evening of Aug. 28 in a borrowed van, then shot him once in the back and twice in the head, taking his money and then dumping his body in a Bountiful church parking lot next to a ball field at 2285 S. Second West.

Boulton, 38, 2436 S. Orchard Drive, was a Deseret Industries employee in Centerville and had been paid $118 that afternoon, Harward said. Anderson, who had previously worked at Deseret Industries with Boulton, knew he had been paid.

Harward, displaying a .22-caliber revolver in court, said it is the gun used in the Boulton shooting and was recovered hidden under a chest of drawers in Anderson's bedroom.

Investigators say the gun is the same one used in the slayings of the Armstrongs, whose bodies were found July 22 near the I-80 overpass at 60th West. The Armstrongs were both shot numerous times, investigators said.

Anderson was charged with second-degree murder, a first-degree felony, in the Boulton shooting and first-degree murder, which can carry the death penalty, in the Armstrong killings.

Valdez and Salt Lake County prosecutor Howard Lemcke told the judge the two first-degree murder charges will be reduced to second-degree murder in return for Anderson's plea of guilty but mentally ill.

The judge asked Anderson if he understood that the five-years-to-life prison terms in the incidents could be sentenced consecutively and that he faces an additional zero-to-five-year enhancement term for the use of a firearm in the crime.

Anderson, who told the judge he has "only so-so" reading abilities and doesn't understand much of what he reads, said he understood and that Valdez and his Davis County public defender, Steve Vanderlinden, had read the guilty plea affidavit to him and explained it.

Anderson's mental abilities were a key factor in the case, with Page ordering a mental evaluation by Davis County Mental Health and then at the Utah State Hospital to determine if he was capable of understanding the charges against him and assisting in his defense.

Page and 3rd District Judge James Sawaya, using the same evaluation, both ruled Anderson competent to stand trial.

Under his guilty but mentally ill plea, Anderson will be returned to the State Hospital for another evaluation, then appear in 2nd District Court May 24 for a sentencing hearing in the Boulton killing.

If he is found not to be mentally ill, he faces a term in the state prison.

If it is determined he is mentally ill, he will be kept in the State Hospital for treatment and, if he is cured, will be referred to the Utah Board of Pardons, which will determine if he should begin serving his prison term or be released on parole.

Harward said he believes the three killings demonstrate that Anderson is a danger to society, and he hopes the prison terms will be imposed consecutively to prevent Anderson from returning to society.