COLUMBUS, Ohio (WCMH) — Andrew Mitchell — the former Columbus police vice officer accused of murder — took the stand in his own defense Friday, as the defense worked to paint a picture of the moment he shot and killed sex worker Donna Castleberry.

“I fired a shot so I could stop the threat,” Mitchell testified, as he took the stand for hours and gave a play-by-play of the events that occurred on Aug. 23, 2018.

Mitchell picked up 23-year-old Castleberry, he testified, and from there, Mitchell and Castleberry discussed prices for a sexual act. When he went to make the solicitation arrest, he said she didn’t believe he was an officer.

He worked to prove he was an officer by showing her paperwork and an ID card. It was then, he said, the attempted arrest turned physical.

“I saw my wound first, before I saw the knife — while we were struggling, I couldn’t believe what I was seeing. It was a deep gash,” Mitchell said.

The physical altercation continued until shots were fired. “I fired a shot so I could stop the threat, to make sure she wasn’t going to shoot, I mean stab me, again,” he testified.

‘Stop the threat’ were words uttered repeatedly by the former vice officer as he worked to tell the jury why he fired several shots inside of the decoy car on the summer day. But the prosecution worked to poke holes in his claims that he was just an officer making an arrest — instead the questioning focused on his unpreparedness.

“You were ill-prepared to do your job on this day, and you knew you would get reprimanded, right?” said Sheryl Prichard, prosecuting attorney, to which Mitchell responded that he did not have his badge.

Prichard also argued he was unable to reassess a quickly changing situation.

After five days in court, the trial will resume Monday at 9 a.m.