Writings
Shortly after the court hearing for the van break-in, Harris reverted his website back to just hosting user-created levels of 
Doom. He began to write his thoughts down in a journal instead. In both of these journals, Harris and Klebold would later plot the attack. Soon after beginning his journal, Harris typed out one plan of attack which included after the massacre possibly escaping to a foreign country or 
hijacking an aircraft at 
Denver International Airport and crashing it into 
New York City.
[11]
Klebold had already been keeping a personal journal since March 1997; as early as November of that year, Klebold had mentioned going on a killing spree. Klebold had used his journal to vent about his personal problems as well as what he'd wear and use during the attack.
[29]
Harris also made entries on topics such as his 
sexuality on his journal where he described the desire for sex with women, especially his desire of 
raping and 
torturing them in his bedroom.
[31] Harris also expressed interest in 
cannibalism and stated that he would like to dismember a woman whom he could have sex with.
[32]
Harris and Klebold also used their schoolwork to foreshadow the massacre.
[h] They both displayed themes of violence in their 
creative writing projects. In December 1997, Harris wrote a paper on school shootings titled "Guns in School",
[35][36] and a poem from the perspective of a bullet.
[37] Klebold wrote a short story about a man killing students which worried his teacher so much that she alerted his parents.
[38][39]
Both had also actively researched war and murder. For one project, Harris wrote a paper on the 
Nazis and Klebold wrote a paper on 
Charles Manson.
[40][41][42] In a 
psychology class, Harris wrote he dreamed of going on a shooting spree with Klebold.
[43] Harris's journals described several experimental bomb detonations.
[29][44]
Nearly a year before the massacre, Klebold wrote a message in Harris's 1998 yearbook: "killing enemies, blowing up stuff, killing cops!! My wrath for January's incident will be godlike. Not to mention our revenge in the commons." The commons was slang for the school cafeteria.
[9]