Eighteen-year-old Arapahoe High School shooting suspect Karl Pierson entered the school on Friday, Dec. 13th firing a total of six rounds, killing himself and fellow student Claire Davis in under one minute and 20 seconds, the sheriff said Monday morning.
Pierson took himself bowling shortly before the shooting, Arapahoe County Sheriff Grayson Robinson said during the news conference, causing some in the media to recall Michael Moore's Academy Award-winning documentary, "Bowling For Columbine" and ask Robinson whether there was any connection during the news conference (although neither Eric Harris nor Dylan Klebold were in their bowling class on the day of the shooting, according to the Jefferson County Sheriff's Office, even though an attendance sheet claimed they were.)
"On the morning of [the shooting], he conducted his activities the way he always did," Robinson said, calling Pierson a murderer instead of addressing him by name. "He took the time to have a meal, and actually took the time to go bowling, by himself, alone." Robinson added that he could not confirm whether Harris or Klebold had gone bowling before the 1999 shooting, but that if there was any connection between Pierson and myths or facts in the Columbine High School shooting, their investigation would uncover it.
Between Dec. 6th and the morning of Dec. 13th, Robinson revealed that the murderer had still been in the planning process and used the time to purchase his weapons and ammunition, which included a 12-gauge pump action shotgun, a machete, 3 incendiary devices and more than 125 rounds of shotgun ammunition.
Robinson also said that the murderer entered through an exterior door that should have been locked, but rarely was and had been left ajar before the shooting.
"This one hits close to home for me," said Arapahoe District Attorney George Brauchler, who added that, "purely coincidentally," the first time he'd met the incoming Arapahoe County Sheriff David Walcher, was the morning of the Columbine High School shooting in 1999.
Brauchler said that authorities continue the investigation and have obtained around a dozen search warrants including for the gunman's home, a car, computers, cellphone and Brauchler suggested that there would be more coming.
"I want to know that there was something that could be done, even if there wasn't," Brauchler said. "It is compelling to get at as much truth as possible."
Back in September, Pierson had been disciplined for making threats against debate coach and librarian Tracy Murphy. Robinson said that the threat "was very specific to the disagreement between the murderer and the speech coach" and that it had been reported to law enforcement, but that they were still investigating how it was handled.
During the press conference, Robinson praised the school's quick response to the shooting, and particularly the quick actions of school resource officer James Englert and an unarmed security guard and retired Arapahoe deputy Rod Mauler for running "to the thunder."
Both Englert and Mauler ran to the library where Pierson was while the school went into lockdown mode. Pierson had already fired three rounds in the hallway and two in the library before taking his own life.
"The reason we say 'run to the thunder' is because of the echo that a gunshot makes down a hallway," Robinson said. "Murderers, once they are found out and once they realize they're about to be overwhelmed, take their own life."
At Davis' memorial on Saturday, Englert will serve as pallbearer.
"James Englert is a hero, there's no question. James responded heroically and he saved lives," Robinson said. "James Englert was given the distinct honor on Saturday to serve as the pallbearer for Claire Davis and he was asked specifically by the Davis family. James Englert will be on duty at Arapahoe High School when the students return on Jan. 6.... he is a very important part of the Arapahoe High school family."
CORRECTION: A previous version of this article incorrectly stated that the Columbine High School gunmen went bowling shortly before the 1999 massacre. The Huffington Post reached out to the Jefferson County Sheriff's Office which confirmed that, despite numerous conflicting accounts of the morning of the shooting, neither Eric Harris nor Dylan Klebold were in their bowling class that day.