By Sky News US Team

The mother of Columbine shooter Dylan Klebold has said "never a day goes by" where she does not think of the people her son massacred.

In her first TV interview, Sue Klebold said she did not know anything was wrong with her son before the 1999 attack that left 13 people dead.
She told told ABC News' Diane Sawyer: "I think we like to believe that our love and our understanding is protective, and that 'if anything were wrong with my kids, I would know.' But I didn't know, and it's very hard to live with that."

Sue Klebold has published a memoir on the tragedy. Pic: ABC News

Dylan Klebold and fellow student Eric Harris also injured 21 others at the Denver high school on 20 April 1999, before taking their own lives.
Mrs Klebold said she believed she was a "good mom", and that she thought Dylan "could talk to me about anything".
"Part of the shock of this was learning that what I believed and how I lived and how I parented was an invention in my own mind - that it was a completely different world that he was living in," she told ABC's 20/20 programme.

Klebold and Harris killed 13 people in the 1999 massacre

:: US Gun Violence: History Of Deadly Shootings
In the interview Mrs Klebold described how she had struggled in the years after the shooting.

"There is never a day that goes by where I don't think of the people that Dylan harmed ... It is very hard to live with the fact that someone you loved and raised has brutally killed people in such a horrific way."

Anne Marie Hochhalter shared a photo of the Klebolds' letter. Pic: Facebook

Anne Marie Hochhalter, who was left paralysed from the waist down after the shooting, said in a Facebook post that she was ready to forgive Mrs Klebold for her son's actions.
The post, written directly to Mrs Klebold, included a copy of what Ms Hochhalter called a "genuine and personal" letter she received from the Klebold family months after the shooting.
In it, Sue and Tom Klebold wrote: "Though we have never met, our lives are forever linked through this tragedy that has brought unspeakable heartbreak to our families and our community.
"With deepest humility we apologize for the role our son, Dylan, had in causing the suffering you and your family have endured."
Mrs Klebold's interview comes ahead of the release of her new memoir, A Mother's Reckoning: Living In The Aftermath Of Tragedy.
Proceeds from the book, set for release on Monday, will be donated to research efforts and charitable foundations focusing on mental health issues.