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LOVELAND, Colo. (KDVR) — For the first time, Rei Mendoza, the man who witnessed a Loveland police officer’s force against Karen Garner, is speaking out.

Garner was 73 years old and suffering from dementia when was injured during the arrest after being accused of stealing from a Walmart. Arresting officers Austin Hopp and Daria Jalali were charged only after the body camera footage went viral.

Long before the video went viral, Mendoza was already sounding the alarm.

Mendoza’s excessive force complaint, issued verbally on the scene to Sgt. Phil Metzler, was dismissed by Metzler. The sergeant can be heard on body camera video accusing the witness of interfering and insisting his officer did nothing wrong.

“I didn’t know he was a sergeant,” Mendoza told FOX31 in his first TV news interview. “I thought he was a normal cop or whatever.”

The bystander and the police sergeant: what happened

“I see her walking, and then I see [Hopp] throwing her to the ground,” Mendoza is heard telling Metzler on body camera video.

During the conversation, Metzler verbalizes what he assumes to be Mendoza’s perception of law enforcement.

“So you have a complete lack of trust of police because you watch the news,” Metzler was recorded as saying.

Metzler, who hadn’t witnessed the use of force, was dismissive and suggested Mendoza could be in trouble for getting involved — accusing him of interfering in the police activity.

“[Hopp] didn’t do anything wrong,” Metzler told Mendoza. “He didn’t do anything wrong.”

‘What they did to her wasn’t right’

Mendoza watched the body camera video of his conversation with Metzler for the first time on Tuesday.

“[Metzler] shouldn’t react like that,” Mendoza said. “He should have been more professional.”

Metzler is still on the force. Records show he and Loveland Police Department leadership approved of Hopp’s use of force as within policy after reviewing the video of Garner’s arrest.

“It’s something that is coming out of my heart to help that lady, because what they did to her wasn’t right,” Mendoza said.

Mendoza told FOX31 Metzler has some work to do if he continues employment in law enforcement.

“If he wants to be the guy in charge, he needs to take more classes or be more polite with people,” Mendoza said.

Metzler can be heard on the body camera recording telling Mendoza he can file a formal complaint at the Loveland Police Department. FOX31 reached out to Loveland police repeatedly for comment on this story. None was provided.