A Casper man admitted Friday to assaulting another man during a fatal attack in Casper this summer.

Jonathan Jelsma, 21, pleaded guilty to aiding and abetting an assault with a deadly weapon as part of a plea agreement with prosecutors, who dismissed a murder charge against him.

With the deal, Jelsma avoids the possibility of a life sentence -- the maximum penalty for second-degree murder. Instead, he will serve no more than 10 years in prison.

Police arrested Jelsma and two other defendants after the July 18 killing of Johnny Shane Moody. Police found Moody lying in an alley on the 700 block of East A Street with stab wounds to his chest and back.

Jeffrey Lee Carter, a 46-year-old acquaintance of Moody's, is charged with his murder. Authorities suspect he stabbed Moody, 48, following an argument.

During a brief hearing in Natrona County District Court, Jelsma acknowledged he kicked and hit Moody before the fatal stabbing.

The defendant said he was playing dice at the A Street Apartments when he heard an argument between Carter and Moody. Then he saw a woman come out and say, "This is the guy who raped me."

Jelsma did not identify who the woman was referring to. However, a witness told police Moody and Carter had been arguing about a woman who'd accused Moody of trying to sexually assault her.

Jelsma said he and another defendant, Juan Carlos Diaz, got involved after he saw the woman being pushed down. Authorities suspect Jelsma and Diaz stepped back before Carter delivered the fatal blow.

Diaz, 16, was initially charged with aiding and abetting second-degree murder. His case is now being moved from adult to juvenile court.

Carter, the only defendant who may still face trial, also appeared in court Friday. His attorney, Dion Custis, asked a judge to push back the trial's Dec. 8 staring date. The judge denied the request.

Reach crime reporter Joshua Wolfson at (307) 266-0582 or at josh.wolfson@trib.com.