Family history is typically passed down through stories and photographs. But for sophomore Sierra O’Mara Schwartz, it’s broadcast in movie theaters across the world.

O’Mara Schwartz, a psychology major from Cambridge, Mass. is the granddaughter of police sergeant John “Jack” O’Mara who is the main character in the action film “Gangster Squad.” She found herself at the center of a mini-media blitz when she published a blog post that went viral on Reddit last week.

“Gangster Squad,” released Jan. 11 claims to be a true-life tale of a secret police force tasked with quashing the mob king who controlled late 1940s Los Angeles. Josh Brolin depicts O’Mara Schwartz’s grandfather.

“I wanted everyone to know what an absolutely incredible man my grandfather was. I don’t want the media to portray him as anything else,” O’Mara Schwartz, a former Hatchet photographer, said. “He deserved to be remembered as a cool guy and not as a gun-crazy man.”

O’Mara Schwartz said she was initially thrilled to see her grandfather’s life on the big screen. In November she uploaded a film still to Facebook that depicts the four main characters – including O’Mara – walking from a blaze of fire. She captioned the photo: “Cool grandparents don’t look at explosions.”

But after a trailer for the film that featured a movie theater shootout was hastily pulled following July’s shooting in Aurora, Colo., O’Mara Schwartz got nervous.

What stuck with her most was what seemed like an extremely embellished representation of violence that turned her beloved grandfather a villain. O’Mara Schwartz said she felt compelled to speak up about the man who her mother said only shot a gun once in his long career with the Los Angeles Police Department.

“That’s when I started realizing how violent the movie was going to be and how unlike my grandfather’s real life it was going to be,” she said. “[That scene] made me feel very embarrassed for my grandfather [along with his colleagues] to be associated with such a heinous crime. It was a mess, and I think it said something about the movie.”

She said the film was hard to watch and took to her personal blog to write a post discussing how the real O’Mara did not rely on violence to crack the case. Nine days later, she posted it on Reddit.com.

“I am the granddaughter of the main character in the movie Gangster Squad, John O’Mara. The movie butchered my grandfather’s life,” she wrote. “This is my story.”

O’Mara Schwartz uploaded a link to her blog, not expecting that when she awoke, it would have 200,000 views. Her inbox was flooded with responses and requests for more.

She said she is using her “tiny amount of mini-influence” to publish a timely anti-gun violence message.

“My main message is that I think it’s a big shame that [the producers] took such an interesting story about so many people that were brilliant and honorable cops who used their brains, ideas and strategies for good and instead thought that it was more appropriate to picture them as these violent, aggressive people,” she said.

Her mother, Martha O’Mara, said the film’s violence was falsified, with gore added to up buzz and ticket sales.

“In real life, my dad was warm and funny,” she said. “He always laughed when he told his stories. He didn’t kill and maim people, but he did scare them out of town.”

Her mother agreed that the film created a forum to discuss gun violence in films like the one about her father, adding that in his case, the cops outsmarted – not outgunned – the bad guys.

The film’s release came one month after the Sandy Hook shooting in Newtown, Conn.

O’Mara Schwartz said she penned the blog post on a plane ride to Los Angeles, not knowing how it would skyrocket her to Internet fame.

“I couldn’t let the situation pass without making a statement,” she said.