I never stop thinking of Columbine victims, says killer's mother

The mother of Columbine High School killer Dylan Klebold has said she had no idea anything was wrong with her son before the attack and thinks about the victims and their families every day.

In a special edition of ABC News' 20/20 current affairs programme - her first TV interview since the shooting - Sue Klebold told presenter Diane Sawyer that before the attack on April 20 1999 she considered herself a parent who would have known something was wrong.