"I was in the school library during the shooting at Columbine," said Craig Scott, who was 16 at the time.
Of the 13 people murdered that day, 10 died in that library, but Scott escaped.
"Then later, it took overnight, but [I] learned that my sister Rachel was the first one that was killed," Scott said.
His older sister Rachel Scott was outside the library having lunch with a friend on the lawn.
"The last moment was, according to Richard, they picked her up by her hair and said do you still believe in God? She said 'you know I do.' And they said 'well then go be with Him.' And she took her last shot through the temple," Scott said.
Rachel's life was stolen at age 17.
The Scott family turned to their faith, and Rachel's writings, for comfort.
"In an essay she wrote, called 'My ethics, my codes of life,' talking about starting a chain reaction of kindness. And she believed that if she showed someone kindness it would start a chain reaction," Scott said.
In the essay, Rachel wrote about her belief that honesty and compassion allowed her to invest in people and look past any prejudice or negative first impressions. She encouraged her readers to give someone three chances before judging them.
Rachel wrote, "I have this theory that if one person can go out of their way to show compassion, then it will start a chain reaction of the same."
The Scott family established a school outreach program to prevent teen violence called Rachel's Challenge.
"We travel around to share her story in schools," Scott said.
Rachel's message has reached 18 million people in the 13 years since Columbine.
There have been other school shootings, but none have affected Scott like the tragedy at Sandy Hook elementary.
"This one has hit a lot harder because these are defenseless little kids," Scott said.
As a survivor, and as a brother, Craig knows what it's like to be in this kind of pain.
"That's what the families in Connecticut are feeling right now. Just a lot of shock. And overwhelming sadness and grief. Especially the parents who lost their little kids. They're just broken. Father's thinking about their little boy or little daughter. And what's probably overwhelming their thoughts right now are their last moments," Scott said.
In Rachel's final moments, she stood up for her faith.
"One of the most powerful forces after a tragedy like this is faith," Scott said.
And it was that faith that helped Rachel's family keep her message of kindness alive.
Click here to learn more about Rachel's challenge.
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