COLORADO SPRINGS, Colo. -- A jury has found a former Fort Carson soldier not guilty of first-degree murder in the slaying of a fellow Iraq war veteran, but convicted him of a lesser charge of conspiracy to commit murder.

Louis Bressler, 25, was convicted Wednesday in the Dec. 1 slaying of Kevin Shields.

Jurors acquitted Bressler of first-degree murder after deliberation, first-degree murder in furtherance of a felony and aggravated robbery.

Bressler's lawyer argued that no physical evidence linked him to Shields' slaying and that two co-defendants, also Iraq war vets, conspired to frame him. The co-defendants have reached plea agreements in Shields' slaying and are serving prison terms.

Bressler faced a mandatory life sentence if convicted of first-degree murder. Conspiracy to commit murder carries a standard sentence of eight to 24 years in prison.

"I know in my heart he killed my son," the victim's mother, Debra Shields of Loves Park, Ill., told Colorado Springs station KKTV. "Whether he was found guilty or not, in my heart he will remain guilty."

Kevin Shields was raised by his grandparents, Madlyn and Ivan Shields of the Rockford, Ill., area. The two sat in the front row of the courtroom with Debra Shields and Kevin Shields' widow during Bressler's nearly two-week trial, which began Nov. 3.

Bressler is one of at least five Fort Carson soldiers who served in Iraq with the 4th Brigade Combat Team and who later were accused of various slayings at home over the past 15 months. A sixth team veteran faces attempted murder charges. An Army task force is investigating whether there are any common factors in the slayings.

Prosecutors said Bressler killed Shields because Shields knew too much about robberies that Bressler and fellow veterans Bruce Bastien Jr. and Kenneth Eastridge planned to commit. They also said Shields had beat Bressler in a fight before the slaying. All four had been drinking heavily.

Shields' family said he was out celebrating both his birthday and news that his wife was pregnant with their second child.

The prosecution's case suffered a blow when co-defendant Bastien refused to testify against Bressler, in violation of his plea agreement. El Paso County District Judge Theresa Cisneros refused a request by Deputy District Attorney Jack Roth that Bastien be compelled to testify.

Bastien is serving a 60-year prison term under the plea agreement that required him to testify against Bressler in Shields' death and in the August 2007 murder of fellow soldier Robert James.

Bastien pleaded guilty to conspiracy to commit murder in James' death. Bressler's first-degree murder trial in James' death is scheduled to begin Dec. 1.

Eastridge testified at trial that he saw Bressler shoot Shields.

Bastien's blood was found on Shields' pants, evidence defense attorney Ed Farry said pointed to Bastien as the shooter. Prosecutors said Bastien had cut his hand shortly before Bressler fired a .38-caliber revolver, hitting Shields three times.