(CNN) -- Chris Martinez, just 20 years old when he was gunned down at a deli Friday in California, dreamed of being a lawyer like his dad.
Now his grieving father, Richard Martinez, has emerged as the public face of gun control advocates in the aftermath of the six killings in Isla Vista.
Three of the victims were shot, including his only son. The gunman also shot himself, police said. Chris Martinez, a college student, had gone to get a snack at the I.V. Deli Mart when the gunman opened fire.
Richard Martinez says his child died because of gutless politicians.
"Where is the leadership? Where is the friggin' politicians that will stand up and say, 'We need to do this. We're gonna do something,'" he told CNN. "Those gutless bastards did nothing. And my son died because of it. And it's outrageous. Absolutely outrageous."
Martinez told CNN that he was furious that lawmakers had done nothing since the Sandy Hook Elementary School killings in Connecticut in December 2012. His son died, he said, because of that inaction.
Their inaction was not just related to gun laws; it also was in the lack of progress toward solving a mental health crisis, he told CNN. The two issues are interconnected, he said.
At the same time he grieves for his son, he feels for the parents of the 20 children and six adults who died at their elementary school.
"Those parents lost little kids. It's bad enough I lost my 20 year old. I had 20 years with my son," he screamed through tears. "That's all I'll ever have. Those people lost their little 6- and 7-year-olds. How do you think they feel? And who's talking to them now? Who's doing anything for them now?"
Congress's efforts to enact stricter federal gun laws fizzled in April of last year, when a bill that included stronger federal background checks for gun purchases failed to pass the Senate.
'We need to hold them accountable'
Sen. Richard Blumenthal, a Democratic member of the Judiciary Committee, told CBS that if the Assault Weapons Ban of 2013 had passed, it would have provided more mental health resources in addition to strengthening the background check system.
"I really sincerely hope that this tragedy -- this unimaginable, unspeakable tragedy -- will provide an impetus to bring back measures that would keep guns out of the hands of dangerous people who are severely troubled or deranged, like this young man was, and provide resources. We need mental health resources," the senator from Connecticut said.
Sen. John Thune, a Republican from South Dakota, said legislative debate should center on mental health issues related to violence.
"I think that is something on which there is agreement," he told CBS. "And that is where we ought to be focusing our efforts."
Rep. Adam Schiff, a California Democrat, said the Sandy Hook mass killings should have been enough to motivate Congress.
"We are taking steps to deal with the mental health issues, but obviously we've made very little progress, and it shows in these tragedies," he said Sunday on CNN's "State of the Union with Candy Crowley."
Bob Weiss, whose daughter Veronika was killed outside a sorority house, said he wasn't ready to get political about the issue.
"I do know this, the people who write the laws, they work for us ... and we need to hold them accountable," he told CNN's Sara Sidner. "If we're not holding them accountable, then we're accountable."
"What about Chris' right to live?"
On Sunday, Martinez also gave a passionate statement to the media, saying: "We don't have to live like this. Too many have died. We should say to ourselves, 'Not. One. More.'"
The Brady Campaign to Prevent Gun Violence issued a statement agreeing with Martinez and blaming the National Rifle Association and other gun rights groups for blocking political progress. Martinez also pointed a finger at the NRA for his son's death.
"They talk about gun rights. What about Chris' right to live?" he said angrily.
The NRA has not commented publicly since the killings. The organization also waited several days after the Sandy Hook attack before issuing a statement.
"Out of respect for the families, and as a matter of common decency, we have given time for mourning, prayer and a full investigation of the facts before commenting," the statement after Sandy Hook said. "The NRA is prepared to offer meaningful contributions to help make sure this never happens again."
Martinez said he anticipated the NRA would say he's being overly emotional.
"I think I can be emotional and rational at the same time," he said.
He said he wanted to be an advocate for the victims and to honor his son, who liked sports and competition and was an English major at the University of California at Santa Barbara.
"If there's all these things in the media about the shooter and nothing about the victims, it sends the wrong message," he said. "People need to understand that real people died here."