By Keith Coffman

DENVER (Reuters) - The mother of Columbine shooter Dylan Klebold prayed for him to commit suicide when she was told he was a suspect during the shooting spree at a Colorado school that killed 13 people, the woman said in a new book.

Klebold, 17, and classmate Eric Harris, 18, went on a rampage at Columbine High School in Littleton, near Denver, in April 1999. They were heavily armed and took the lives of 12 students and a teacher, before turning their guns on themselves.

Sue and Tom Klebold, who have rarely commented publicly about their son, were interviewed extensively for a book released this week, "Far From the Tree: Parents, Children and the Search for Identity."

The massacre was the most deadly mass shooting ever to occur at a U.S. high school, and it led schools across the country to adopt tighter security measures and institute lockdown drills. It generated debate over gun laws and put a spotlight on bullying and cliques in schools.

Sue Klebold told "Far From the Tree" author Andrew Solomon that police informed her during the shooting that her son was a suspect and she had a "sudden vision of what he might be doing."

"And so while every other mother in Littleton was praying that her child was safe, I had to pray that mine would die before he hurt anyone else," the book quotes her as saying.

Sue Klebold also said she feared her son would eventually be sentenced to death if he was captured and tried.

Dale Todd's son Evan was a sophomore when he was hit with a shotgun blast, leaving him among over 20 people wounded that day. Dale Todd said he was incredulous when he read Sue Klebold's comments, which Reuters emailed to him, because he found them to be "all about her and her feelings about herself."

Sue Klebold wrote a piece about her son that was published in 2009 by Oprah Winfrey's magazine "O," but she and her husband have largely avoided the media since the massacre.

In the book, Tom Klebold said that his son, Dylan, suffered from being an outcast at his school, and that might have led to his participation in the massacre.

The book also describes an arrest of Eric Harris and Dylan Klebold that took place the year before they went on a rampage. In that incident, previously reported in the media, the two teenagers were caught stealing equipment from a van, but authorities released the boys to their parents' custody, instead of keeping them in jail, and put them in a diversion program.

Tom Klebold said that on the day after the arrest, he went for a walk with his son and found the boy to be angry and feeling his actions was somehow justified. "The morality of the whole thing escaped him," Tom Klebold said in the book.

"Far From the Tree" is about parents of unusual children, such as those who commit crimes or have mental illnesses, but also those who are gifted.

(Writing by Alex Dobuzinskis; Editing by Doina Chiacu)