Yesterday at work

Here's the basic story. I had come out of my building and saw a man carrying a woman by her throat, savagely pummeling her as he dragged her toward his pickup truck. I shouted at him, the gist of which was to stop, that he couldn't do this ...to people, that this was wrong, that it's not okay for him to do this, that he had to knock it off. He threw the woman into the passenger seat and slammed the door and turned to me, screaming and swearing at me. He walked up to me and cursed me out, telling me to get out of here before he f'ed me up. I simply continued to say, "Man you've gotta stop! This is not okay! You can't be tearing people up", etc. He screamed and shouted at me, and I actually thought he was going to hit me. I went onward toward my car and tried to get my cell phone out to take a photo of his license plate. He saw me do this and ran to his truck cab and got a handgun, a glock-style pistol. He pointed it directly at me at arm's length and came at me shouting at me again. "What the F are you gonna do? Get the F out of here before I blow you MF'ing head off!" I told him, "I'm out, man. I'm done. I'm not in your business--I'm leaving." He continued to hold the gun at me and walked me back to my car; I walked backwards to keep facing him. When I got to my driver's seat, he turned and ran back to his pickup. He'd torn out of the parking lot before I even had my seat belt on. I called my coworkers, who put me on speaker phone and called 911 so that I could talk to them while this was being reported to LE at the same time. I began to drive randomly around the area, and saw his pickup truck at a light. I took a photo of it while trying not to be seen in his mirror (so the photo is obscured). I talked to an officer and texted my photo to him. I gave him a detailed description of the man and his car. About 20 minutes later, the officer called me back and said, "I just got the guy! I got him, got the woman, got his gun, got his truck." He told me to come identify the guy by sight within an hour, so I turned around and went back. It was him. The officer told me that the description had been so detailed that he'd been able to spot the guy driving, because by sheer luck the guy had been stopped at a light while the officer drove past. The woman was beaten and her face had a very long cut from top to bottom on it. I had to fill out a report, and the officers told me that the guy will be charged with two counts of assault with a deadly weapon and one count of kidnapping. They regard me as one of the crime victims, and plan to use my statement to help convict him. The woman gave a statement to police too, which corroborated my account, and the guy was taken to jail and is ineligible to bond out. After all this happened, the woman got out of the police car and ran up to me, saying "Thank you! Thank you! He was going to kill me!" She wasn't exaggerating; he had left a 4-minute message on her phone telling her he was coming to kill her, that she was a dead woman, that she needed to dig her grave, etc. Turns out, this guy has some prior issues with larceny and violent offenses.