DENVER — In the first detailed public remarks by any parent of the two Columbine killers, Dylan Klebold’s mother says she had no idea her son was suicidal until she read his journals after the 1999 high school massacre.

Susan Klebold’s essay in next month’s issue of O, The Oprah Magazine, says she is still struggling to make sense of what happened when her son and Eric Harris killed 12 students and a teacher in the shooting rampage at Columbine High School in suburban Denver. Twenty-one were injured before Klebold and Harris killed themselves. “For the rest of my life, I will be haunted by the horror and anguish Dylan caused,” she wrote. “… I’d had no inkling of the battle Dylan was waging in his mind.”