Richard Martinez's only child, 20-year-old Christopher Michaels-Martinez, was killed in the shooting rampage Friday in Isla Vista, California. But he doesn't want your sympathy.

"I don’t give a shit that you feel sorry for me,” he said in an interview with The Washington Post.

What Martinez wants, instead, is this: "Get to work and do something."

The former criminal defense lawyer, who grew up on a farm with guns, has become an unlikely face in the nation's gun control debate, turning grief into rage into action. He has been unafraid of the spotlight, delivering an emotional speech to reporters just hours after learning of his son's death. In the days since, he has appeared on primetime TV and in published interviews, slamming policymakers for their inability to stop the indiscriminate shooting deaths of Americans.

Speaking at a memorial ceremony on Tuesday at the University of California, Santa Barbara, Martinez blamed his son’s death on gun rights groups like the National Rifle Association and the politicians who take their money.

“There haven’t been any leaders on this issue,” he said, to the crowd of mourners, many of them students. “They have done nothing, and that’s why Chris died, and the other kids.”

"It's almost become a normal thing for us to accept this," he said of America's frequent mass killings. "It's not normal ... life doesn't have to be like this."

He then asked the crowd to stand with him and, raising his fist, urged them to chant, "Not one more!" — "so loud they will hear you in Washington." It continued reverberating around the stadium long after he left the stage.

The phrase "not one more" became a hashtag, too. Martinez asked students to tweet it at Tuesday's memorial. It had been tweeted nearly 30,000 times as of Wednesday afternoon, the latest rallying cry used by those fighting for sensible gun laws.

Tweets about "#NotOneMore"

Speaking to The Washington Post, Martinez said he was "going to ask every person I can find to send a postcard to every politician they can think of with three words on it: 'Not one more.'"

“People are looking for something to do," Martinez said. "I’m asking people to stand up for something. Enough is enough.”

Inspired by Martinez's statements, the gun control group Everytown — a coalition group that includes Moms Demand Action and Mayors Against Illegal Guns — launched a digital campaign that allows people to do just that.

"We were inspired by his words, and we agree that every political leader needs to hear this message that 'not one more' child should be killed, not one more person should die because of our weak gun laws," Erika Soto Lamb, the group's communications director, tells Mashable. "So we built this tool to make it easy for all of us to fulfill Mr. Martinez's wishes and to honor his son's life and the lives of the 86 Americans that are killed with guns every day."

For each person who signs up, Everytown will send a postcard to that person's representative in the House, two senators and governor. As of Wednesday afternoon, the group had solicited over 150,000 sign-ons, meaning 600,000 elected representatives will soon be getting the very postcards Martinez called for.

Not one more: http://t.co/QxPP1Zlsm3 pic.twitter.com/jLTDAnRxKW

— Mike Bloomberg (@MikeBloomberg) May 28, 2014

When asked about any coordination between Martinez and Everytown, Soto Lamb said no, but added that her group would love to work with him in the future.

Other groups have already begun reaching out.

In a CNN interview (above), an emotional Martinez wondered: "To have a kid die, because in this kind of a situation, what has changed? Have we learned nothing? These things are going to continue until somebody does something, so where the hell is the leadership? My kid died because nobody responded to what occurred in Sandy Hook."

After the interview, the parents of the victims of that massacre at the Connecticut elementary school posted an open letter for Martinez on Facebook.

Writing on the page for Sandy Hook Promise, a nonprofit group for family members of the children killed at Sandy Hook, the father to one 7-year-old victim welcomed Martinez to the "extended family."

Dear Richard Martinez,

We have not met, but you are now part of our extended family. It is not a family we chose, but a family born from the horrible circumstance of losing a child to gun violence—one that’s only growing each day. My heart breaks for you because I know just a little about the long road ahead of you. We have reached out to you privately but publicly we wanted to say to you and those feeling the sorrow, anger and frustration of this weeks' shooting, you are not alone. It has helped me, and some of the other family members who lost children and family at Sandy Hook Elementary, to come together and advocate for common sense solutions to expanding programs for mental wellness and gun safety solutions. You will find your own path down this difficult road. But know that we are here for you and all of you who have been touched by this tragedy. Together we can and will build a safer world for all our children.

With deepest sympathy,

Mark Barden

Though Martinez has the spotlight now, he is surely aware of the frustrations felt by many of those affected by previous gun massacres. In the year after the Newtown shootings, no changes were made to federal gun laws, and nearly two-thirds of new state laws loosened restrictions on gun ownership.

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