Purcell was shot in the head on his mother's front porch on May 16, 2011, and died the next day.
The attorneys allege that three of the witnesses who testified were purchasing, selling and using methamphetamine on a regular basis during the days before and after the crime, which affected their observations. Also, two of the witnesses admitted to not sleeping for days during that time period, defense attorneys wrote.
Morris and Logue were charged in June 2011 with first-degree felony aggravated murder after a confidential informant told police that Yuri Sanchez Lara, 32, had hired Morris to hurt Purcell.
According to charges, Lara offered Morris an ounce of methamphetamine to injure Purcell, whom Lara thought had worked as a confidential informant with Orem police. Morris was given a half-ounce before the shooting and the rest after Lara learned Purcell was in the hospital, charges state. Logue allegedly was with Morris at the time of the shooting.
Lara pleaded guilty in 4th District Court on Oct. 2 to manslaughter, a second-degree felony, reduced from first-degree felony aggravated murder. He also pleaded guilty to four first-degree felony counts of possession of a controlled substance in connection to heroin, cocaine, methamphetamine and ecstasy that were found in his car when he was arrested in Purcell's death. He was sentenced to spend five years to life in prison.
William Thompson, who bought drugs from Lara and is one of the witnesses in question, testified during the preliminary hearing that Lara had wanted to hurt Purcell because he thought Purcell had told police about a cache of methamphetamine kept in Lara's storage unit.
But Orem Police Officer Scott Spieth testified that Purcell was not the person who informed on Lara, rather it was a woman who was caught with methamphetamine.
Prosecutors have not yet filed a response to the motions, and no court date has been set to discuss the issue.