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The gunmen who kept six girls hostage in a Colorado high-school classroom for hours this week before killing one, then himself, left a long note with his brother that mentions suicide, Park County police said Friday.

"We're still analyzing the content of the note," Sheriff Fred Wegener told reporters, adding that one of the weapons found in Duane Morrison's possession was traced back to a family member of the shooter. The 14-page note — in which Morrison wrote, 'this is not a suicide note' — was sent to Morrison's brother and was received Thursday and was mailed on Wednesday.

"However, many times, the letter references suicide. This letter clearly acknowledges his pending death. It also apologizes to his family for his actions that will occur," Wegener said.

"It doesn't tell me a lot of 'why' but it does maybe tell me that the conclusion of the events of the 27th may have been my worst fears — that he probably intended to kill both the young ladies and then kill himself, or have us shoot him."

There were originally six female hostages but Morrison, a 53-year-old petty criminal, released four before the shooting began.

Investigators were piecing together evidence Friday to try to determine the motive of Morrison, who sexually molested all six girls during a four-hour standoff with police, and sexually assaulted at least two of them, after bursting into a college prep English class at Platte Canyon High School.

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"They were molested and I think they all were molested but I don't know how much or to what degree, and to be honest, I'm not sure I want to say," Wegener said Friday, adding that, as a parent, his heart goes out to the families of the hostages.

"It's a healing process that will take some time but I couldn't be more proud to be part of this community," he said with tears in his eyes.

The letter Morrison sent to his brother didn't say how he was going to kill himself, nor did it detail his plans for this week's attack at Platte Canyon High School, Wegener said. The note apparently is a long, rambling piece in which the man talked about personal pain he'd been experiencing. Wegener said it appears the note was written over several days.

Morrison also reportedly wrote that he knew family members would probably be angry with him because of publicity surrounding the end of his life.

Investigators found the note after agents from the federal Bureau of Alcohol, Tobacco and Firearms traced ownership of the handgun used in the killing to the brother, who then said he'd received the letter. The second gun used was also tied to Morrison. A rifle found about a mile from the school at what appears to be a makeshift campsite was still being investigated by ATF agents.

Authorities said they knew of no connection between Morrison and the hostages but said he was living in a hotel in the Denver metro area.

On Thursday, Wegener said the suspect approached a male high school student Wednesday and "asked about the identity of a list of female students." The sheriff said he wasn't sure if it was a written list or names rattled off by Morrison.

It was not disclosed whether the list included 16-year-old Emily Keyes, whom Morrison shot in the head one time as a SWAT team broke through the classroom door in a rescue attempt.

On Friday, Wegener encouraged reporters and others to not be so quick to criticize the school's security procedures.

"Let's get a handle on what happened before we start making criticism," Wegener said.

He noted that after the 1999 shooting at nearby Columbine High school, a school safety officer was installed at Platte, and more training procedures were put into place "that I believe made us better and I believe it made the school better."

"I was just thankful we had those procedures in place," he added.

'I Just Knew It Wasn't Good'

KCNC-TV in Denver reported that video from cameras outside the school showed Morrison sitting in his Jeep in the school parking lot for about 20 minutes and then mingling with students as classes changed, nearly 35 minutes before the siege began.

Morrison walked inside the school with two handguns and a backpack that he claimed contained a bomb. Student Chelsea Wilson said she was in the classroom when the gunman came in and told the students to line up facing the chalkboard.

"All the hairs on my body stood up," she said. "I guess I was somewhat praying it was a drill."

One by one, the gunman started letting students go. Chelsea, a tall brunette, said she was the first to leave. Her mother, Julia Wilson, said she thinks the gunman selected the blond, smaller girls. Keyes' yearbook photo shows a smiling blond girl with blue eyes.

Chelsea said she heard what might have been a gunshot after she left the classroom.

"He's a pervert," she said. "I'm not sure of motivation. I just knew it wasn't good."

While still holding two girls, he cut off contact with deputies and warned that "something would happen at 4 o'clock," authorities said.

About a half-hour before the deadline, a SWAT team used explosives to blow a hole in a classroom wall in hopes of getting a clear shot at him. When they couldn't see him through the gap, they blew the door off the hinges to get inside, said Lance Clem, a spokesman for the state Department of Public Safety.

Morrison fired at the SWAT officers, shot Keyes as she tried to run away and then killed himself, authorities said. During the gun battle, police shot Morrison several times.

Text Message: 'I Luv U Guys'

The sheriff said he spoke to Emily's family and explained his decision to try to take Morrison by force.

"They were surprisingly supportive of everything I did," Wegener told CBS. "They are extraordinary people indicating that are going through a rough time. I hold the responsibility for Emily in my heart. I'll live with that for the rest of my life."

Classes were canceled for the rest of the week as the community tried to come to grips with the bloodshed, which evoked memories of the 1999 shooting rampage that left 15 dead at Columbine High School, less than an hour's drive away.

Louis Gonzalez, a spokesman for the Keyes family, said the girl's father was among the parents anxiously awaiting word from their children during the standoff. John Keyes had just bought Emily and her twin brother cell phones for their 16th birthday.

"How are U?" a volunteer text-messaged Keyes on her father's behalf.

At 1:52 p.m., she messaged back, "I love U guys."

"In memory of Emily we would like everyone to go out and do random acts of kindness, random acts of love to your friends or your neighbors or your fellow students because there is no way to make sense of this," Gonzalez said. "It's what Emily would have wanted."

Residents of this mountain town of about 3,500 gathered Thursday at the Platte Canyon Christian Church for support.

"It's very sad here. You know, the family lost their daughter but as a community, we lost a child," said Bobbi Sterling, a waitress and cook at Cutthroat Cafe, where Keyes had worked. "We're just sitting here, numb and in shock. We're all just kind of stunned."

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The Associated Press contributed to this report.