The drifter who took six girls hostage at Platte Canyon High School in Bailey, Colo., and sexually assaulted some of them before fatally shooting one and killing himself as police stormed the classroom left a suicide note, authorities said.
The gunman, identified as 53-year-old Duane Morrison, was a former carpenter with no apparent ties to the community and a history of minor criminal offenses. Sheriff Fred Wegener said Morrison sent the note to a male relative before storming the high school.
Wegener did not release the contents of the note. He said the relative did not live in Bailey. Investigators had traced the handgun used in the shooting to the relative.
The small, close-knit town of Bailey is now mourning the loss of 16-year-old Emily Keyes, who was killed by Morrison during the Wednesday standoff.
Wegener said the assaults of the girls went beyond touching or fondling, but gave no specific details.
"It was pretty horrific," he said.
Witnesses said Morrison made his way into the high school dressed like a student.
"He didn't really look like a student. Well, he did because he was wearing all our school stuff, but, when I saw when he turned around and looked at me," said Platte Canyon High School freshman Jesse Kirby. "He had long, gray hair sticking out of his hoodie."
Authorities said the unmarried Morrison was living out of a Jeep.
"Me and Bobby were walking through the parking lot, and we saw him in the yellow Jeep," said senior Roman Tucker.
Some students weren't initially concerned by the stranger's appearance on campus.
"It looked as if he was just going to pick up one of his kids," said senior Bobby Wright. "We didn't think anything of it."
One mile north of the school, agents discovered a makeshift campsite, along with an assault rifle, that could have belonged to Morrison.
"I think anybody who goes in -- an armed individual -- takes on innocent, unarmed children in the sanctuary of a school is the lowest of the most cowardly of the most yellow," said Joe Morales, executive director of the Colorado Department of Public Safety.
Platte Canyon's emergency plan is credited with isolating Morrison from the majority of students, but not all schools are prepared for such a crisis.
"Very often, we find that schools have crisis plans on paper, but many of those plans are outdated," said Kenneth Trump, president of National School Safety and Security Services. "Academics and safety should not be in competition. They go hand in hand."
Authorities still have not determined the suspect's motive.
"We're hoping that through the investigation, that hopefully we'll find out why," Wegener told "Good Morning America." "I want [there] to be an end to whether it was random or whether it was a very deliberate act."
Wegener said officers were analyzing a security video that showed the suspect in the high school's parking lot before the standoff.
Wegener defended his decision to have authorities storm the classroom.
He said that with the SWAT team in place outside the school, he felt that action needed to be taken.
However, he regrets Keyes' death.
"But I still lost a student, and that's unacceptable," he said.
The sheriff called the Keyes' family "courageous."
"They're holding up quite well," he said. "They expressed a lot of appreciation. … I definitely appreciated just the opportunity to talk to them."
Wegener went on to thank agencies like the Colorado State Patrol and the Bureau of Alcohol, Tobacco, Firearms and Explosives for their help with the investigation.
"It's just been a wonderful show of support," he said.