Richard Martinez, whose son was shot and killed in the University of California, Santa Barbara, massacre, has become a powerful voice in the U.S. gun control debate by telling politicians: “I don’t care that you’re sorry. Do something.”

Martinez’s only son, 20-year-old Christopher Michaels-Martinez, was one of six people slain last Friday when Elliot Rodger went on a killing spree in the California community of Isla Vista before shooting himself.

Martinez blames his son’s death squarely on American politicians and the National Rifle Association, which has lobbied fiercely against tougher gun laws, even in the wake of multiple horrific school shootings.

“There has to be a tipping point. There has to be a point where enough is enough,” Martinez told CBC Radio’s As It Happens on Thursday.

“It’s ridiculous,” he said, that people in the U.S. now believe school shootings are a problem that can’t be solved, and are just a normal risk of life.

Martinez emerged as a potent gun control advocate at a memorial held at UC Santa Barbara when, despite being emotionally devastated, he paid tribute to his son and blasted politicians for their inaction.  

"They have done nothing, and that's why Chris died," Martinez told the crowd, before leading them on a chant of “Not one more!”

Since then, numerous members of Congress have contacted Martinez.

“The ones that have called have said, ‘I’m sorry and I want to express…’ and at that point, I say ‘I’m not interested. I don’t care that you’re sorry. Don’t waste my time. Don’t waste your time,'" Martinez said.

“I’m not asking for their sympathy. I’m not asking for their prayers. I’m asking them to do something.”

Martinez is calling for a crackdown on the sale of assault weapons and the ability to hoard ammunition.

He also urged the media to not use the shooter’s name or image and not broadcast his ideas following the shooting, saying it’s “completing the plan” the shooter had.

“There’s not one solution to the problem,” Martinez cautioned.

He said he now intends to devote himself to learning about what causes these shootings and how to stop future attacks.

“I refuse to accept that we continue to live with this problem,” Martinez said.

“I don’t want anyone else to have to go through this,” he said, before breaking down. 

With files from The Associated Press