Federal prosecutors will not be allowed to use a key piece of evidence — a 3-D animated model — in the trial of the FBI agent accused of lying about his role in the shooting of LaVoy Finicum.

In the trial that begins next month, prosecutors will attempt to prove that FBI Special Agent Joseph Astarita fired two shots at Finicum two years ago and then lied in an attempt to cover up the gunshots.

Neither shot hit Finicum, but Astarita’s role in the incident has become a rallying point for people who are critical of the government’s role in the shooting.

Finicum was shot and killed by Oregon State Police troopers after he attempted to drive through a roadblock set to capture leaders of the Malheur National Wildlife refuge takeover.

The 3-D model created by computer animation and reconstruction expert Toby Terpstra shows the approximate position of everyone at the roadblock. In creating models of the scene, Terpstra used eyewitness video, including footage from FBI planes overhead and a cellphone video shot by another refuge occupier inside Finicum’s truck.

The model in question shows Astarita — a member of the FBI’s elite Hostage Rescue Team — in a shooting position with his rifle aimed at Finicum’s vehicle. In a hearing last month, defense lawyers described Terpstra’s work as closer to “graphic art” rather than something accurate enough for a jury to see.

On Monday, Judge Robert Jones agreed with the defense, at least in part:

“The still frames he used did not provide clear images of the individuals, only fuzzy smudges. The images were of such poor quality that I am unconvinced that this methodology could accurately place the location of the individuals and the positions in which they are posed in the model,” Jones wrote. “The clear image of the model depicting defendant with his rifle shouldered and trained on Finicum’s truck was not the product of a reliable methodology and involved excessive subjectivity.

“To present it to a jury would suggest a degree of certainty that cannot be justified and would be unduly prejudicial,” Jones wrote in the ruling.

Jones said prosecutors can use a 3-D model to show the location of vehicles at the roadblock when Finicum was shot.

Still, it’s a blow to prosecutors. The defense has repeated at nearly every opportunity its contention that the government lacks both eyewitnesses and any ballistics evidence against Astarita.

Astarita has pleaded not guilty to two counts of obstruction of justice and three counts of making a false statement. His trial starts July 24 and is expected to last several weeks.

Jones did allow prosecutors to use several other expert witnesses and pieces of forensic evidence that defense lawyers had opposed. He ruled, for example, that jurors could determine whether to rely on evidence presented by an audio engineer who prosecutors will use to establish when the shots were fired that allegedly came from Astarita.