It has almost been two decades since the Columbine High School massacre took place, and Beth Nimmo, mother of the first victim, a devout Christian, Rachel Joy Scott, is still choosing to forgive her daughter's killers.

That fateful day, 18-year-old Eric Harris and 17-year-old Dylan Klebold gunned down 12 students and teacher, Dave Sanders, before turning the guns on themselves. The first person they killed was Scott, 17. She was simply enjoying lunch with her friend on a grassy patch when she was shot.

Harris and Klebold thought she was already dead after shooting her three times, according to Scott's friend Richard Castaldo who witnessed the killing. But when they saw signs of life, they approached her and asked, "Do you still believe in God?" She answered without hesitation, "You know I do." Her killer then answered, "Then go be with Him" and shot her again.

Remarkably, Nimmo tells the Daily Mail that she is "thankful" for this knowledge of Scott's bravery in her final moments.

"It brings me comfort to know that Rachel died for the one thing she was willing to die defending and that was her faith," she says. "I believe Rachel had peace when she faced the gun and faced her killer. I can't prove it but I choose to believe that Rachel had peace and that she went from the presence of evil to the presence of the Lord in that split second."

Nimmo adds that Sue Klebold, Dylan's mother, wrote a 'heartfelt' letter of apology to the family of each victim after what her son did. Because she reached out, Nimmo reciprocated by meeting with her.

"She was just as fearful of meeting me as I was of her. I didn't know what I was going to say to her," recalls Nimmo. "This was the mother of one of the boys who shot my daughter. I asked the Lord what would you have me say to this woman? I have no idea."

When they finally met, Nimmo simply asked Sue to tell her who Dylan was before April 20, 1999. She was surprised how tears just fell from Sue's eyes as she told her about "this precious little blond, curly haired boy that they loved and cherished just as much as I loved and cherished my little Rachel," she says.

Nimmo says she has nothing but respect for Sue, and she and her family have made a conscious effort to forgive the two boys who cost them their daughter's life.

"Forgiveness is me saying, what you did to me is not okay but I choose to forgive you because I'm not going to live in the pain of that for the rest of my life. You're not going to control me because I'm not going to let what you did to me define me for the rest of my days," she explains.

Scott's story has been translated into a film called "I'm Not Ashamed," from the makers of God's Not Dead, that will be released on October 21, 2016.