SAN FRANCISCO, Calif. – An undercover video is exposing the type of folks leading the teachers union in San Francisco, and how they plot to protect educators who abuse students.

Project Veritas, a group led by conservative video journalist James O’Keefe, released secretly recorded video footage Tuesday of United Educators of San Francisco treasurer Antonio Mankini explaining to an undercover journalist how he assaulted students and “made it look like an accident.”

MORE NEWS: Know These Before Moving From Cyprus To The UK

The video centers on the journalist, posing as a teacher, soliciting advice from Mankini on behalf of a colleague who he said felt guilty for striking a student. Mankini told the journalist the teacher has nothing to worry about if “there’s no evidence” and explained how he has evaded punishment for the same scenario in the past.

“Were there any witnesses? Just keep it that way. Seriously. If there weren’t any witnesses, it’s your word against the kid’s. Kids f*cking lie. Seriously,” Mankini said in the video, which was posted to YouTube.

“But if there were no witnesses, then you have that deniability and that’s something that could be used,” he said. “No I didn’t do it. There’s no scars, marks, … or bruises or anything. There’s no evidence.”

Mankini told the journalist during the November 2015 meeting that “teachers have smacked kids before. And … sometimes they’re still working.”

“I’ve seen it go away more than anything else,” Mankini said. “A lot of kids don’t come forward with it. It’s how they’re treated at home.”

Mankini, who taught for years in the district but is now on leave to work for the union, also explained the “right” way to smack students around.

“I spent 17 years working with law enforcement so I know ways to … It’s like I told them, I could hurt you and never leave a mark,” he said.

MORE NEWS: How to prepare for face-to-face classes

“Elbows are awesome weapons too,” he said.  “They are harder than a fist …”

The union official even relayed his own experiences with ruffing up students.

“I clotheslined a kid in a class one time, you know and of course I was pretending, I was pointing at the kids and the kids saw the kid went down,” Mankini said. “I mean, he ran into my arm. He wasn’t supposed to be in my class and of course I caught him here and he went down backwards.

“And that one still bothered me,” he said. “That one, yeah, because I crossed the line. I know, I mean, I made it look like an accident and all the witnesses would have said no he ran into my arm because he ran into me. I didn’t reach over and knock him down, you know. He ran into me.”

Mankini is only the latest target in a years-long undercover sting by Project Veritas of teachers union officials across the country, an effort that also exposed corruption within the Yonkers Federation of Teachers in New York, among others.

The group has also successfully exposed political scandals within CNN, NPR, Planned Parenthood and the liberal community organizing group ACORN.

San Francisco union spokesman Matthew Hardy told CBS San Francisco the union placed Mankini on administrative leave as officials investigate the video.

“I can only speak to the comments on the video. When we do our investigation, if we determine it’s accurate we will take action as necessary,” he said. “We are going to get to the bottom of it. We are deeply committed to students’ safety and we will act as swiftly as we can once we have the full information.”

San Francisco Unified School District officials, meanwhile, are asking any students who had been abused by Mankini to come forward.

“We have grave concerns about the behavior of Mr. Mankini references and encourage any former students, staff or family members who may have experienced mistreatment from Mr. Mankini or any other district employee to report their concerns immediately,” spokesman Blythe Gentle told the news site.

Mankini left the classroom to work for the United Educators of San Francisco in 2014, NBC Bay Area reports.