"We have not met, but you are now part of our extended family," Mark Barden wrote in a Tuesday Facebook post. Barden's 7-year-old son, Daniel, was killed in Newtown, Conn., in 2012.
"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," Barden continued.
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.
Video of Richard Martinez's public display of grief and outrage in the wake of his son's murder was widely circulated over the weekend.
"We don't have to live like this. Too many have died. We should say to ourselves, 'Not. One. More,'" an emotional Martinez told reporters.
In a subsequent interview with CNN, Martinez said he still grieved for the parents of the children who died at Sandy Hook.
"Those parents lost little kids. It's bad enough I lost my 20 year old. I had 20 years with my son," he said. "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?"