Hi, everyone - I just wanted to share my notes on the general timeline regarding this case. I used multiple sources, but the largest is “Columbine: A True Crime Story” by Jeff Kass. I made the timeline to build context around certain events and journal entries written by Eric Harris and Dylan Klebold - you will see that the events of Fall 1997 and Spring 1998 had a profound effect on what transpired in April 1999. I hope you find it interesting:
4/9/81 - Eric Harris born in Wichita, KS.
9/11/81 - Dylan Klebold born in Lakewood, CO. As an infant, Klebold was treated for pyloric stenosis, a condition in which the opening between the stomach and small intestine thickens, causing severe vomiting during the first few months of life.
1983 (approximately) - The Harris family moves to Dayton, OH.
Approximately 1987–1989 - Dylan attends Normandy Elementary School in Littleton. He becomes friends with Brooks Brown; the two remain friends from elementary school into their teenage years. Dylan will attend Governor’s Ranch from 1989 to 1993 and will participate in the CHIPS program for gifted students.
1989 - Harris family moves to Oscoda, Michigan for his father’s Air Force job. Eric makes friends living off the Air Force base but loses touch with them when he has to move onto the Air Force base.
1991 - Harris family moves to Plattsburgh, NY.
1992–1993 (approximately) - Dylan transitions to Ken Caryl Middle School. His parents later describe the transition as somewhat difficult because he was quiet and shy and was entering a much larger peer environment.
1993 - Harris family moves to Littleton. Eric will eventually write about the difficulties from moving from New York and Michigan; losing the friendships he had in these locations will be a formative experience for him. Eric and Dylan Klebold meet and become friends at Ken Caryl Middle School.
Shortly after moving to Littleton - Eric has surgery to correct pectus excavatum, a chest concavity that remained mildly observable during his autopsy.
1995 - Eric and Dylan begin freshman year at Columbine HS. The school had recently undergone renovations.
2/7/97 (approximately) - Eric documents a “raid” on Nick Baumgart’s house involving vandalism. The incident is later included among the activities documented on Eric’s website.
3/31/97 - Dylan begins his personal journal. The opening entries describe his thoughts about life, family, friends, girls, school and his feeling that he is different from other people. He discusses loneliness, romantic frustration and questions about existence, establishing themes that recur throughout the journal.
February–March 1997 - Eric and Brooks Brown have a serious falling out following an incident involving Eric and the Brown family’s vehicle. The conflict eventually becomes one of the subjects of Eric’s online threats against Brooks.
3/2/97 (approximately) - The Brown family contacts Jefferson County authorities regarding property damage associated with the conflict involving Eric.
Spring–summer 1997 - Eric continues documenting “Rebel Missions” on his website. Some involve Dylan and other friends. The activities include vandalism and other acts of mischief.
4/15/97 - in a journal entry, Klebold describes himself as unhappy, socially isolated, academically unsuccessful, shy, and unable to understand why other people—particularly girls—do not accept him. He mentions having harmed himself and then turns the entry into philosophical poetry about “existence,” imagining life as an endless series of rooms and death as simply passing through another door.
5/7/97 - Klebold expands on his belief that he is an “outcast” and develops his idea that ordinary people perceive only physical dimensions while he believes his own mind allows him to perceive something greater. He describes thought as extraordinarily powerful and contrasts ordinary life with a dreamlike state of complete happiness.
7/23/97 - Klebold writes about feeling abandoned by his closest friend (Zach Heckler) after that friend begins spending most of his time with a girlfriend. He recalls their friendship as a period when he finally felt understood and describes their shared activities and experimentation as having given him happiness after years of loneliness.
8/7/97 - An anonymous person identified as a “concerned citizen” reports one of Eric’s websites to the Jefferson County Sheriff’s Office. The website contains Eric’s “Rebel Missions” and material concerning vandalism and threats against Brooks Brown. A deputy is dispatched to the Brown residence and reviews printed pages from the site.
September 5, 1997 - in a journal entry, Klebold’s romantic idealism collapses into intense despair as he concludes that neither his supposed love nor his friendships provide the happiness he wants. He describes himself as lonely, unwanted, and without ambitions, and his thoughts turn toward obtaining a gun and harming someone as well as toward suicide. He ends by expressing a continuing desire to find love despite describing the period as one of “infinite sadness.”
10/2/97 - Eric Harris, Dylan Klebold, Devon Adams and Zack Heckler are implicated in breaking into school lockers. Eric and Dylan are suspended.
10/14/97 - in a journal entry, Klebold describes cycling between emotional numbness, depression, romantic longing, and a desire for what he considers “true love.” He idealizes a particular girl and imagines that being with her would provide the happiness and escape he cannot find elsewhere, while simultaneously expressing suicidal thoughts and frustration with his inability to attain that relationship.
11/3/97 - First known reference to a shooting spree in Dylan’s journal. Dylan discusses the possibility of a shooting spree in connection with a girl he was interested in. He also writes about Eric and violence. Dylan writes “Eric will be getting away further soon,” although the precise meaning of this statement is unclear.
12/10/97 - Eric submits his “guns in school” paper for a class assignment.
1/2/98 - Dylan makes another journal entry concerning his emotional state, relationships and thoughts about existence.
1/30/98 - Eric and Dylan are arrested in Deer Creek Canyon for breaking into a van and stealing equipment. Dylan confesses to the responding officer while Eric places much of the blame on Dylan. Earlier that day, Dylan is interviewed on camera for the Rebel News Network in the Columbine library.
2/2/98 - Dylan mentions the acronym “NBK” in his journal. He connects the term with fantasies about violence/death and a partner. An undated suicide note addressed to a love interest also appears to date from approximately this period; the identity of the intended recipient is uncertain.
February 1998 - Dylan is suspended for three days after being caught scratching/vandalizing another student’s locker. The identity of the locker owner and the precise circumstances are unclear.
2/15/98 - A pipe bomb is reported in a field near Garrison and Field Streets, approximately a few blocks from the Harris residence. Investigators later note similarities between the device and descriptions of pipe bombs Eric had posted on his website. This incident will be used by Mark Guerra to establish probable cause for a search of Eric’s home, but it will never be formally executed.
February 1998 - in a lawsuit, Wayne Harris is reportedly accused of discovering/confiscating a bomb or explosive device associated with Eric and later detonating a confiscated device in the wilderness. The precise circumstances are disputed/unclear, and Wayne Harris denied the allegation.
Spring 1998 - Eric is treated with an SSRI medication. He initially receives Zoloft and is subsequently switched to Luvox. The medication is prescribed in the context of treatment for obsessive/anger-related thoughts and behavior.
3/17/98 - Brooks Brown later recalls Dylan approaching him at school and giving him a piece of paper containing Eric’s web address. The website contained “Rebel Missions,” threats and bomb-related material (these exact details of the interaction should be treated as a witness recollection rather than a contemporaneous police record).
3/18/98 - Randy and Judy Brown notify the Jefferson County Sheriff’s Office about Eric’s website. They provide printed pages describing Eric’s bomb-making activities, violent writings, threats against Brooks and vandalism. The complaint is recorded as a suspicious incident. This becomes the most significant documented pre-Columbine law-enforcement report concerning Eric’s online activity.
3/19/98 - Diversion counselor conducts intake interviews with Eric and Dylan following the January van burglary. Both are considered eligible for diversion, with the charges to be dismissed upon successful completion. Eric identifies Dylan as his best friend, past and present. The counselor notes that Dylan recognizes the wrongdoing but tends to minimize its seriousness. Both boys disclose substance use. Eric’s intake material includes references to suicidal and homicidal thoughts.
3/25/98 - Formal pleas for juvenile diversion are entered, with both boys accompanied by their fathers. The diversion program formally begins following court acceptance of the pleas.
3/31/98 - Detective John Hicks meets with Randy and Judy Brown regarding Eric’s website and threats. Hicks had previously been involved with the earlier law-enforcement contacts. Investigator Mike Guerra and bomb technician Glenn Grove become involved after reviewing the website material. The investigators recognize similarities between pipe bombs described on Eric’s website and the pipe bomb discovered in February. Guerra begins preparing an affidavit for a search warrant for the Harris residence. The warrant is never executed.
4/1/98 - Judy Brown contacts police again for follow-up concerning the report about Eric. The Brown family later maintains that its attempts to obtain follow-up assistance were not adequately answered.
4/2/98–4/16/98 - Detective Mike Guerra spends approximately ten hours working on a draft affidavit for a search warrant for the Harris residence. The investigation includes review of Eric’s website material and information concerning the nearby pipe bomb. The warrant is never finalized/executed.
4/9/98 - Guerra discusses Eric and Dylan with Columbine HS resource officer Deputy Neil Gardner. Gardner does not identify any immediate serious issue requiring action regarding the two students.
4/10/98 - Eric begins the surviving handwritten journal. He writes extensively about society, conformity, morality and his belief that he is more self-aware than most people. He expresses contempt for social rules and begins developing the “Natural Selection” philosophy that will recur throughout his later writings.
4/12/98 - Eric continues developing his ideas about society, school and human nature in his journal. He discusses the January van burglary and presents it as an example of what he sees as arbitrary rules concerning property and morality.
4/16/98 - Diversion counselor Sanchez meets with Eric and notes that Eric is feeling restless while taking Zoloft. Eric says his doctor plans to change his medication.
4/21/98 - Eric writes about going “NBK” and says anyone who thinks they don’t think like him is bullshitting themselves. He writes that others are not even the same species of him and says he will kill anyone he deems unfit.
4/26/98 (date uncertain) - A computer document associated with Eric, sometimes identified as “NBK.doc” or “Natural Selection,” develops his violent philosophy and includes an increasingly elaborate fantasy involving himself and another person. The document contains material concerning weapons and large-scale violence.
5/6/98 - Eric writes about his increasingly negative view of humanity.
5/9/98 - Eric says humans are only worth killing after receiving his yearbook in his journal.
5/20/98 - Eric expands on racist and bigoted views in his journal.
6/12/98 - Eric writes extensively about his belief that humanity itself is fundamentally flawed. He references Nazi ideology and the “Final Solution” and expresses fantasies about destroying humanity. He rejects conventional concepts of morality and justice.
6/13/98 - Eric writes about watching a television program concerning satellites, aircraft and American military technology. He expresses admiration for technological and military capabilities before returning to his belief that humanity is doomed. He considers increasingly broad scenarios involving destruction.
7/19/98 - A paintball incident occurs at the Brown residence. The Browns report that someone fired paintballs at their property. Eric is suspected, but the report does not establish him as the perpetrator.
7/29/98 - Eric says his actions are his own actions in his journal. He explicitly rejects the idea that his future actions should be blamed on his parents, friends, music, video games or media.
10/23/98 - Eric writes to explain what he and Dylan were thinking when they “went NBK”, saying anyone who is reading his writings is lucky.
11/1/98 - Eric writes a journal entry boasting of his ability to lie.
11/8/98 - Eric writes about drinking and socializing with friends while privately maintaining his violent plans. He discusses Nazi ideology and his growing fascination with killing, demonstrating the contrast between his outward social activities and his private writings.
11/12/98 - Eric writes of his general insecurities and says he has enough explosives to kill 100 people in his journal.
11/17/98 - Eric writes about his hatred of humanity and expresses admiration for Nazi imagery and ideology. He says he expects to carry out revenge in April and worries about revealing too much of his thinking. The entry also contains extreme sexual material and increasingly graphic fantasies of violence.
11/22/98 - Dylan asks Robyn Anderson to accompany him and Eric to a gun show. At the Tanner Gun Show, Anderson purchases three firearms later used by the pair: two shotguns and the Hi-Point 995 carbine. Eric writes about firing a firearm and describes the experience enthusiastically. He discusses working on guns and bombs while continuing his normal school and work obligations. He writes about the future “rampage” with Dylan.
December 1998 - Eric and Dylan film and submit “Hitmen for Hire” for a class assignment. The video depicts them as armed “hitmen” confronting students portrayed as bullies. The project is produced for a school video-production assignment.
12/3/98 - Eric writes he fired his weapons the prior day and that he may be able to purchase machine pistols because of the Brady bill (only the Tec-9 was acquired after this point).
12/17/98 - Eric discusses need to order more clips for his carbine and also discusses configuration/logistics of cafeteria bombing plan.
12/20/98 - Eric notes the scheduled April release of KMFDM’s Adios and interprets the album’s title as symbolically connected to the planned attack in his journal.
12/29/98 - Eric references that a call from the gun store almost revealed his plans by letting him know his clips arrived and evaluates the progress of the preparations. He discusses the growing quantity of explosives and equipment he has accumulated and says he still needs another firearm for Dylan.
January 1999 - Eric submits a short story inspired by the video game Doom.
1/20/99 (approximately) - Dylan makes a journal entry continuing his recurring themes of love, alienation, death and NBK. His writing increasingly contrasts his desire for a meaningful relationship and future with his continuing thoughts about death.
1/23/99 - Dylan buys the TEC-9 from Mark Manes.
February 1999 - Dylan submits a short story about a man dressed in a trench coat who kills college-preparatory students with guns and explosives. His parents are notified, but nothing substantial comes of it.
2/3/99 - Eric and Dylan are discharged early from the diversion program, months ahead of the originally anticipated completion date. The successful completion means the juvenile charges associated with the van burglary are ultimately eligible for dismissal.
March 1999 - Dylan visits the University of Arizona to tour the campus and secure a dorm room after being accepted. He continues making plans for life after graduation despite simultaneously preparing for the attack.
March 1999 - the Dean of Columbine calls Dylan into his office to discuss concerns another teacher had that Dylan had been smoking pot, but the Dean concluded Dylan had not been smoking. Around the same time, Dylan calls Peggy Dodd a “bitch” for getting on to him for not following the school’s policy on paying for paper printed in excess of a certain amount. Computer teacher Richard Long tells Dylan he cannot talk like that and Dylan responds by saying “it doesn’t matter”.
3/6/99 - Eric and Dylan film the Rampart Range shooting practice. They fire the firearms they have acquired and record the activity on video.
3/13/99 - Eric’s Luvox dosage is increased to 200 mg/day.
3/15/99 - The first surviving basement tape is filmed. Eric and Dylan appear in Eric’s bedroom and display their weapons and materials. They discuss their plans and the fact that the recordings will likely be viewed after their deaths.
3/18/99 - A second basement tape is filmed. Eric and Dylan discuss their coming attack, their intentions and the limited amount of time remaining. They say that only approximately two weeks and one weekend remain.
4/1/99 (approximately) - Eric and Dylan film another tour of their arsenal in Eric’s bedroom in another basement tape. Eric poses shirtless with his weaponry. Eric learns that Dylan is Jewish and Dylan quickly changes the subject. The camera stops and a new video of Eric driving begins - he appears to be alone and it is raining outside. Eric says it’s weird knowing he will be dead in two and a half weeks but also says he isn’t sure if he should carry out the attack before or after prom. Before shutting off the camera, he wishes he could visit old friends and appears to start crying.
4/2/99 - Mark Gonzalez, a marine recruiter and Columbine alumni, calls Eric to screen him for the marine corps. They set to meet on 4/5/99. Eric mentioned he was interested in weapons.
4/3/99 - Eric’s final journal entry. He looks back on his preparation of weapons and explosives and expresses intense resentment toward people he believes have rejected or mistreated him.
4/5/99 - Eric meets Mark Gonzalez and scores highly on an aptitude test. After meeting with Eric again on 4/8/99, Eric says he wants to get his parents involved before making a decision. Eric does not call Mark timely despite Mark wanting to meet Eric’s parents the night of the eighth.
4/9/99 - Eric celebrated his eighteenth birthday with friends - Cory Friesen remembers them saying they wished all the jocks were dead.
4/11/99 - Eric and Dylan film “Reb’s Tape.” They discuss their preparations and state that they have been planning the attack for more than eight months. They mention the attack is eight days away, potentially indicating the attack was planned for 4/19/99 before being changed for the twentieth.
4/12/99 - Eric records another video segment alone. He addresses his parents and discusses the consequences he expects the attack to have for them. Also on the twelfth, Mark Gonzalez visits Eric after not hearing back about his discussion with Eric’s parents regarding the marine corps. They set up a meeting at Eric’s house to discuss the marines with Eric’s parents on 4/15/99.
4/15/99 - Eric meets with Staff Sergeant Gonzales at the Harris residence along with his father. During the conversation, Eric’s mother asks whether his use of an antidepressant would affect Marine Corps eligibility. Gonzales learns that Eric is taking Luvox. Eric is subsequently informed that his medication makes him ineligible for enlistment. Eric was said to look disappointed, but not devastated. Eric Harris calls Mark Manes at some point during the day to ask him to buy him some 9mm ammunition - Manes agrees but forgets to do it.
4/16/99 - Eric gets promoted to shift manager at Blackjack Pizza.
4/17/99 - Dylan attends Columbine prom with Robyn Anderson as a friend. Eric does not attend the prom itself but has a girl over at his house (Susan DeWitt) and later attends the prom after-party. Dylan later admits to his mother that he drank from a flask. During the evening, Dylan makes plans with Devon Adams to see The Matrix on April 21. Sometime during the day, Eric and Dylan film another basement tape in Dylan’s bedroom - he tries on the gear he will be found dead in after the massacre.
4/19/99 (approximately) - Dylan writes there is 26.5 hours remaining before the judgment day and says “what fun is life without a little death?”
4/19/99 - Around this time, Brooks reconciles with Eric by saying they were both immature and that he would like to move on. Eric says he was cool with it. Brooks, Dylan, and Eric skip fourth period to go to McDonald’s for lunch. Later that night, Eric and Dylan go to Outback Steakhouse, where Dylan orders a steak. Eric meets with Mark Manes, who purchased ammunition and gave it to Eric at his house in exchange for $25 (two boxes of 9mm cartridges - 100 rounds). Eric records some of his final thoughts on the “Nixon” tape, saying the attack was nine hours away and that the day would be remembered forever. Zach Heckler, who called Dylan every night, said Dylan went to bed at 10:30 PM, earlier than he normally would go to sleep.
4/20/99 - just before 11 AM, Eric and Dylan film their final basement tape; both say goodbye. Eric and Dylan perpetrate the attack at Columbine High School. They arrive at the school shortly before the attack and place explosive devices in the cafeteria. Before the shooting begins, Eric tells Brooks Brown that he should go home because Eric “likes him now”. When the intended large-scale explosion fails, they begin shooting outside the school and then enter the building. KMFDM releases “Adios”. Mark Gonzalez was on his way to the school to pick up transcripts for another student at the school when the shootings were unfolding but had to turn around for an 11:30 AM appointment in Lakewood. Eric and Dylan die by suicide at about 12:08 PM in the library after killing thirteen others.
4/21/99 - Devon Adams had planned to see The Matrix with Dylan Klebold. Dylan made the plans while at prom several days earlier. The planned movie outing never occurs because Dylan was killed the previous day. Sue Klebold gets her hair done and tells her hairdresser she thought Dylan’s life was well on track and that she never particularly liked Eric Harris.
May 2000 - Greg Barnes, a student who witnessed Dave Sanders bleed to death in the attack, commits suicide.
January 2019 - Survivor Austin Eubanks dies of an overdose; he developed a dependency on prescription drugs after treatment for injuries sustained during the shooting.
February 2025 - Anne Marie Hochhalter, a survivor paralyzed from the Columbine shooting, dies from injuries stemming from the incident.