Harris was a psychopath and Klebold battled depression, according to psychologists cited in the book.

CNN: Debunking the myths of Columbine, 10 years later

Shoels' family was not expected to attend, nor would Harris and Klebold be mentioned in the ceremony.

CNN: Columbine seniors graduate under the shadow of shooting

Records have since been released disputing that Klebold and Harris were outcasts or the targets of bullying.

CNN: Columbine left its indelible mark on pop culture

Twenty-three others were injured, and the two shooters -- Dylan Klebold and Eric Harris -- killed themselves.

CNN: Columbine seniors graduate under the shadow of shooting

Cullen, the original Columbine debunker, theorizes that the public was afraid to believe Harris and Klebold weren't total outcasts.

CNN: Debunking the myths of Columbine, 10 years later

Harris and Klebold were not members, Cullen concluded after talking to students at the school and analyzing police documents.

CNN: Debunking the myths of Columbine, 10 years later

Kass was able to get Klebold's college application essay through public records requests.

CNN: Debunking the myths of Columbine, 10 years later

Klebold took a date to the prom, riding with a dozen friends in a limo, just days before the shooting.

CNN: Debunking the myths of Columbine, 10 years later

Many people have asked why the parents of Littleton gunmen Eric Harris, 18, and Dylan Klebold, 17, didn't know that their teen-agers were making homemade bombs and doing other preparations for the assault.

CNN: Town meeting looks at lessons from Littleton

It is not known if Harris actually took the medication, and investigators said Wednesday early toxicology tests performed by the medical examiner's office showed no evidence of drugs or alcohol in the body of either gunman, Harris or Dylan Klebold.

CNN: Columbine shooter was prescribed anti-depressant