After kicking a man in the face so severely that it caused him a traumatic brain injury, Christopher Reiter never wrote in a report when he was a Minneapolis police officer that he feared the man had a knife. None of the other officers on the scene the night of May 30, 2016, wrote anything about a knife, either.

More than a year later, Reiter testified Thursday during his trial for third-degree assault that he was told the man he kicked, Mohamed Osman, had a knife. He said he needed to use force to protect his partner.

“I thought he had a knife. I thought he had it out,” Reiter, 38, said. “I thought he was engaging [another officer].”

Reiter was the first to respond to the Midtown Exchange building in south Minneapolis on an assault report. He found a woman whom Osman had badly beaten, and then heard on the radio from another officer at the scene that Osman was parked in an SUV outside the building.

Surveillance video shows several officers surrounding Osman as he sat on the driver’s side. He got out with his hands up, then knelt to the ground, when he was kicked twice by Minneapolis officer Josh Domek. Reiter then rounded around the car door and kicked Osman in the face, causing him to collapse unconscious.

Reiter’s argument that Osman was armed was bolstered in the afternoon by testimony from the woman whom Osman beat. She told the Hennepin County jury her last words to Reiter before he left her to confront Osman.

“Be careful,” she said she told Reiter. “This guy has a knife. Be careful.”

Reiter told the jury that when he came to the apartment building that night he had never before seen such violence inflicted on someone. He appeared to choke back tears as he described the woman’s injuries, barely able to describe them.

He said that after the woman told him about Osman having a knife, he feared Osman had come back to kill her.

When Reiter ran outside the apartment building, his view of Osman was blocked by the SUV. When he rounded the car and saw Osman, he told the jury he thought Osman was resisting Domek.

The video shows Osman rising up after Domek kicked him.

Reiter said he had two seconds to make a decision. He described the kick as “more of like a slap to the face with my foot.”

“If you believed he had a knife, did you feel authorized to use deadly force?” Reiter’s attorney, Robert Fowler, asked him.

“Yes,” Reiter replied.

Reiter was fired by the Police Department after the kicking incident.

During his cross-examination, prosecutor Dan Allard attacked Reiter’s credibility

“Where are your notes from the case?” he asked.

“Gone,” Reiter replied. “When I found out I was fired, I got rid of everything I no longer needed.”

“So you destroyed them?” Allard quickly shot back.

“Yes,” Reiter said.

In his official report on the incident, Reiter wrote nothing about the domestic-assault victim telling him about a knife. He also acknowledged never writing that he worried about another officer being in danger.

“You made a conscious decision to not put those details in the report?

“Correct,” Reiter said.

“Because you were, what, tired and?” Allard asked.

“Tired, fatigued and felt like absolute crap,” Reiter said.

Allard wanted Reiter to answer why he didn’t radio to other officers at the scene about Osman having a knife. Reiter said that he was running and that it would have slowed him down to run and speak into a microphone at the same time.

“Are you saying you’d be unable to run and speak into a microphone at the same time?” Allard asked.

“No,” Reiter said.

And when a supervisor came to the scene that night to get information about the use of force, Reiter acknowledged that he never told her about the knife, either.

“You know that it’s a big deal for the [Minneapolis Police Department] when force is used by one of your officers?” Allard asked.

“I suppose,” Reiter responded.

The day’s testimony put Allard in a position of not only trying to prove Reiter to be not credible, but also the woman Osman pleaded guilty to assaulting. He told Judge Fred Karasov that he wanted to call rebuttal witnesses next week to challenge the woman’s testimony about the knife. That might include the prosecutor who worked on her domestic-assault case.

She testified that after the assault, she told the prosecutor, Adam Tomczik, about Osman having a knife.