Seven years later, counselor Harriet Hall still isn't sure what sparked the deadly rampage at Columbine High School, but she believes the nation is better prepared to deal with such violence.
"We are sadder and wiser," said Hall, lead mental health counselor for survivors of the 1999 massacre that left a teacher and 14 students, including both gunmen, dead.
In nearly 1,000 pages of essays, diary entries, computer files and other documents released Thursday, the suicidal gunmen, Eric Harris and Dylan Klebold, wrote about hate, violence and their step-by-step plans as they gleefully plotted the deadliest school attack in U.S. history.
"Hell on Earth — ahh, my favorite," Klebold wrote in Harris' 1998 yearbook above a drawing of a gun-wielding headless soldier. "So many people need to die."
The papers also included a journal kept by Harris' father that referred to his son's disciplinary and psychological problems but shed no light on whether he knew the teen might be capable of the murder.
More than 20,000 documents and videos have been released since the Columbine attack. The latest release followed a lawsuit filed by the Denver Post.
The documents offer a chilling insight into the killers in the months before the attack. Klebold and Harris had "to do" lists, with each purchase of a gasoline or a weapon marked off, and they had a hit list with at least 42 entries (all redacted).
"Once I finally start my killing, keep this in mind, there are probably about 100 people max in the school alone who I don't want to die, the rest MUST (expletive) DIE!" Harris writes in a journal entry from October 1998, six months before the attack.
The pages are filled with profanity, racial slurs and drawings depicting violence or death. A scrawled entry in a Klebold day planner apparently sketches out April 20, 1999, down to the minute, starting with a 6 a.m. meeting, a 10:30 a.m. "set up," an 11:12 a.m. "gear up" and at 11:16 a.m., "HAHAHA."
Remarking on the possibility that the two might survive, Harris wrote they would try to escape to a foreign country where they couldn't be extradited. If not, they'd crash a plane into New York City with them inside.
The material also includes Wayne Harris' journal with entries addressing threats made by his son against classmate Brooks Brown more than a year before the attack. The Brown family reported the threats in early 1998 and still contends the authorities or the Harrises should have taken action against the boy.
"We feel victimized," Wayne Harris wrote. "We don't want to be accused every time something happens. Eric is not of fault. Brooks Brown is out to get Eric. Brooks had problems. ... manipulative con artist."
Wayne Harris' attorney did not return a call seeking comment.
Brown said Eric Harris had "lied about everything to his father and made him believe he was innocent and everyone else was the evil party."
Brown's father, Randy Brown, said the sheriff's office should release everything, including the videos and audiotapes from the killers. The sheriff has declined to release the tapes out of concern they could inspire copycat attacks.
"There are lessons to be learned," Randy Brown said. "This information will be hidden forever. They are trading their cover-up for the lives of children in other schools."
Hall, the survivors' counselor and CEO of Jefferson Center for Mental Health, said many of the lessons have already been learned.
"Our best practices for how you respond have changed, and a lot of that happened because of Columbine," she said.