"That day on April 20, I was just with my friend Rachel Scott. We were kind of sitting there," Castaldo said.
They were sitting outside during their lunch break when Eric Harris and Dylan Klebold began shooting. Richard and Rachel were the first two students hit.
"They shot us both pretty much at the same time. It was all kind of one big spray," Castaldo said.
Castaldo remembers bleeding for over 30 minutes before help arrived.
"During that time, I heard Rachel crying and stuff. They came back and shot her in the head, and I knew she was dead after that," Castaldo said.
Like he fought to stay alive 13 years ago in Colorado, Castaldo is now fighting to keep his condominium in Southern California. Like millions of Americans, Richard is about to lose his home to foreclosure.
He went to Los Angeles five years ago to attend a sound engineering school with dreams of pursuing a career in music. The Hollywood condo he bought in 2008 seemed like a good investment.
"I feel kind of stupid, honestly, because I should have known better. I kind of bought into the notion that of course the condo was going to go up in value which, of course, obviously it hasn't," Castaldo said.
Castaldo's story echoes so many others. He was advised to take an interest only loan to buy an overpriced property. Last year, he fell behind on his mortgage payments. There were plenty who promised they could help.
"I get mailing every day from somebody, but of course, they all want money up front," Castaldo said.
He turned to a group that knows about eviction. Occupy LA. Ever since their encampment was evicted from City Hall, they've made it their mission to help homeowners facing foreclosure.
"I'm not bitter in terms of me. I'm bitter that stuff like that in Aurora keeps happening. It doesn't seem like it's ever going to change," Castaldo said.
Change is what Richard was looking for when he came to California. He doesn't want to go back to Colorado. He says California is his home now.
Nate Chisholm contributed to this report.
(KUSA-TV © 2012 Multimedia Holdings Corporation)