The public Facebook post, dated July 18, began with the ominous question that many war-time veterans dread: "'What's it like being shot at?'"
"A question people ask because it's something that less that 1% of our American population will ever experience," Roybal's post said. "Especially one on a daily basis. My response has always been the same, not one filled with a sense of pride or ego, but an answer filled with truth and genuine fear/anger."
Based on photos, the 28-year-old US Navy veteran appeared to have served in Kandahar, Afghanistan, with the 25th Infantry Division, a US Army division that has seen heavy fighting in both Iraq and Afghanistan.
Roybal then goes on describing his first firefight and the lingering effects that appeared to resonate - long after his return home:
"Finishing up what was supposed to be a quick 4-hour foot patrol, I remember placing my hand on the [armored vehicle] and telling ["Bella"] how well she did. Hearing the most distinct sounds of a whip cracking and pinging of metal off of the vehicle I just had my hand resting on is something that most see in movies.
I remember that first day, not sure how to feel. It was never fear, to be honest, mass confusion. Sensory overload...followed by the most amount of natural adrenaline that could never be duplicated through a needle. I was excited, angry and manic. Ready to take on what became normal everyday life in the months to follow. Taking on the fight head on, grabbing the figurative "Bull by the horns".
Unfortunately, as the fights continue and as they as increase in numbers and violence, that excitement fades and the anger is all that's left. The anger stays, long after your friends have died, the lives you've taken are buried and your boots are placed neatly in a box in some storage unit. Still covered in the dirt you've refused to wash off for fear of forgetting the most raw emotions you as a human being will ever feel again."
So far, his post has received nearly 900 likes.
"What's it like to be shot at? It's a nightmare no amount of drugs, no amount of therapy and no amount of drunk talks with your war veteran buddies will ever be able to escape," Roybal's post said. "Cheers boys."
Roybal was at the country music festival celebrating his birthday with his mother, Debby Allen, when he was shot in the chest. The two were separated amid the chaos, according to KABC.
Although a fireman was present after Roybal was shot, he was unable to revive him due to the sustained rate of fire from the shooter, Allen said.
"He saw Christopher take his last breath," Allen said.
"Today is the saddest day of my life," Allen wrote in a Facebook post. "My son Christopher Roybal was murdered last night in Las Vegas. My heart is broken in a billion pieces."