TULSA, Okla. (CN) – An Oklahoma police union filed an ethics complaint Wednesday against Tulsa County District Attorney Steve Kunzweiler, claiming he indicted former Officer Betty Shelby for the shooting death of unarmed black motorist Terence Crutcher too quickly due to public and political pressure.

The Tulsa Fraternal Order of Police filed the grievance with the Oklahoma Bar Association, saying Kunzweiler “rushed to charge” Shelby with manslaughter. It says the investigating detective later called the shooting justified, and that the manslaughter charge was filed before the “prosecution packet” was complete.

“Upon information and our belief, Kunzweiler was told before he filed the charge that Sgt. [David] Walker was of the opinion that the shooting was justified under the circumstances and his report would reflect that,” the ethics complaint states, according to the Tulsa World. “A few days after Kunzweiler filed the criminal charge, Walker’s report did find the shooting justified; Kunzweiler had done no other independent investigation.”

Union chairman Jerad Lindsey told reporters at a news conference that the grievance was filed to prevent Shelby’s case setting a precedent of public and political pressure rushing an indictment “before all the evidence is in.”

Shelby, 42, is seen in helicopter and dashboard camera video exiting her police cruiser near a disabled SUV in September, while Crutcher, 40, is shown slowly walking away from her with both arms in the air.

Crutcher walks toward the driver side of the SUV and is hidden from view as the police helicopter circles around the passenger side. He then slumps and falls to the ground after being shot. No weapons were found on Crutcher or in his car.

Shelby pleaded not guilty to first-degree manslaughter. She said Crutcher appeared to be on drugs, did not respond to her commands and that she feared he was reaching for a weapon through a window. A medical examiner determined Crutcher had PCP in his system when he died.

“We believe DA Kunzweiler seems to have unfairly and unethically rushed to charge Officer Shelby before all of the critical evidence has been provided and reviewed, contrary to the way he normally handles all other cases, including police-related shootings,” the grievance states.

Lindsay said the timing of the grievance was not meant to influence Shelby’s trial, which begins Monday.

“Nothing that we are doing here will be entered into evidence or used in the trial,” he said. “We waited so long because we kept expecting something big to be revealed [by prosecutors] to make this all make sense. It never came.”

Kunzweiler’s spokeswoman Sally Van Schenck was present at the union’s news conference. She said her boss has not been able to review the grievance, as the office is busy preparing for Shelby’s trial.

Shelby has expressed sadness at Crutcher’s death, but said in April that Crutcher’s actions dictated hers, and that “he caused his own death.”