Lara never revealed to Thompson who killed Purcell, but he knew who it was: Darrell Morris.
Thompson testified that he introduced Lara and Morris to one another at his Spanish Fork home earlier that month.
Lara had asked Thompson if he knew of anyone who could hurt someone, Thompson testified, telling him that he intended to hurt 32-year-old Purcell.
"He thought someone [Purcell] was going to snitch on him or whatever," Thompson said.
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.
Spieth said he had never even heard Purcell's name until evidence at Lara's storage shed connected Purcell to the alleged drug dealer.
Lara, 32, is charged with first-degree felony aggravated murder for allegedly hiring two other men, Darrell Wayne Morris, 39, and Danny LeRoy Logue, 46, to hurt Purcell.
Purcell was shot in the forehead in the early morning hours of May 16, 2011, and died the next day at a hospital.
Morris and Logue are also charged with aggravated murder. Utah County prosecutors have said they will not seek the death penalty. The three men are also charged with multiple drug-related counts.
But the preliminary hearing, which is set to last through Friday, is only for Morris and Logue. Lara is scheduled for a plea entry hearing on Oct. 2.
According to charges, Lara contacted Morris to kill Purcell in exchange for an ounce of methamphetamine. 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.
Purcell's family identified Lara as a possible suspect because the two had dealt drugs together and they were engaged in an ongoing dispute concerning payment for a car Purcell had sold to Lara, according to charges.
Also charged in connection with the slaying was Robin Jackson, 37, of Beaver, who pleaded guilty in July to a reduced count of third-degree felony attempted obstructing of justice for withholding information from police about the alleged murder weapon.
Jackson, who was dating Logue at the time of the slaying, was present when the gun was allegedly sold to a Centerville man for a gram of methamphetamine, according to charges.
The man, who allegedly purchased the gun, has not been charged, and documents indicate he was cooperating with police.