A Casper man convicted of attempted first degree murder says he did not get a fair trial.

Public Defenders for 27-year old Zacharia Johnson have filed a motion for a new trial, arguing that a co-defendant...Robert Simmons...would not make any statements during Johnson's trial, because the prosecution interfered with what was going to be Simmons' testimony.

Simmons' reasons for pleading the fifth, were that he did not want to face false swearing or perjury charges, because he is already facing a similar charge in an unrelated case.

Natrona County District Attorney Mike Blonigen has countered saying that Johnson and Simmons had already been identified by witnesses at the time of the crime.

The incident in question was the stabbing of 61-year old Robert Masterson, back in March 2013.

A few days after the stabbing, Simmons drove his car off of a cliff in Mills, and into the North Platte River, and later told medical personnel that he did it because he was trying to "atone for his sins for stabbing a guy the other night."

Blonigen also mentioned in court documents, that the prosecution has not spoken to Simmons, aside from when he entered a plea deal for charges connected to this case.

During Johnson's trial, the defense said that if Simmons would not answer questions, they would attempt to offer his previous hearsay statements as evidence, but prosecutors said if that was allowed, then they should also be allowed to offer hearsay statements to rebut or impeach that testimony.

The defense then abandoned their pursuit of Simmons' testimony.

A judge will rule on the motion for a new trial at a later date.

Simmons is currently serving 20-to-25 years in prison, after he pleaded guilty to charges connected to this case.

Johnson is waiting to be sentenced, and could receive life in prison.