In 2009, at age 15, Christina Grimmie began uploading videos of herself singing on YouTube. She quickly became an internet sensation, amassing millions of fans and went on to perform on “Ellen,” “Dancing With the Stars” and more.

But Christine Grimmie’s biggest break came in 2014 when she placed third on NBC’s “The Voice.” With the full support of her mother, father and brother, Christina Grimmie chased her dream of becoming a professional singer. She went on to perform her own music to sold out crowds on global tours.

“It’s kind of a blur just thinking about it,” Marcus Grimmie said. “It really changed our lives.”

In a special episode of “LA Stories,” host Giselle Fernandez revisits her conversations with Marcus Grimmie, who opened up about how their lives changed once more.

After a performance in Orlando in 2016, during a routine fan meet-and-greet, Christina Grimmie was shot and killed. Her brother saw the attack unfold and tackled the gunman to the ground. The killer then turned the gun on himself.

Orlando police said that without a doubt, Marcus Grimmie’s actions prevented what likely could have been a mass shooting. The following evening, 49 people were gunned down at the Pulse Nightclub. That tragedy, on the heels of his own, highlighted to Marcus Grimmie the distinct loss of attention on the victims and their families.

“When the cameras go away and the lights fade out... now they’re left alone with the loss,” he said. “That’s when I think people realize they need the help more.”

In his sister’s memory, Marcus Grimmie and his family set up the Christina Grimmie Foundation to assist families in the wake of gun violence. To date, the foundation has given out more than $400,000 and helped at least 200 families.

This spring, Marcus Grimmie is planning a three-day livestream concert in order to continue to raise money for families. With the recent shooting in Monterey Park, he knows now more than ever that people will need the support the foundation is able to provide.

“It’s never easy to hear about it,” he said. “And unfortunately, we hear about it quite a bit. But we have a great team... and we will just make sure that these families that are affected get the assistance that they need.”

Watch "LA Stories with Giselle Fernandez" at 9 p.m. every Monday on Spectrum News 1.