PORTLAND — When the mother of mass shooter Christopher Harper Mercer got an automated voicemail from her son's college in Oregon about shots fired on campus, she first called the hospital. Then, she called the jail.

Finally, she checked his bedroom to see if any of his many guns were missing.

"I had thought too, well, just play a long shot and I'm just gonna like go check his inventory, his guns," Laurel Harper told police after the shooting.

That long shot turned into a parent's nightmare. By the time she left her son's bedroom, authorities were unraveling police tape around her home.

They confirmed her suspicions: Her son was the shooter who had just killed nine people and wounded eight more at Umpqua Community College in Roseburg.

Douglas County authorities on Friday released a detailed report on the Oct. 1, 2015, mass shooting that includes a six-page, typewritten "manifesto" in which Harper Mercer critiqued the methods of other mass killers and said he was a follower of the occult.

It also includes a lengthy transcript from an interview with his mother, as well as transcripts and summaries of interviews with surviving victims and witnesses.

Randy Scroggins, the father of a then-18-year-old girl injured in the attack, said his family didn't attend a meeting for victims and their relatives Thursday night to hear what would be in the report.

He said he's curious to see it, however, and isn't opposed to authorities releasing the information publicly. The family is healing, he said.

"We're doing very well. She is doing very well. She is not completely over it yet," Scroggins, a pastor, said in a phone interview. "At 18 years old, I'm not sure how anybody can get completely over that, but we're moving on. We're moving forward."

In a brief printed statement, Umpqua Community College President Debra Thatcher called the report a step in the community's healing process. She praised the depth of the investigation and asked for space as residents and students process the newly revealed details.

In his manifesto, the 26-year-old Harper Mercer wrote that he is part of a "demonic Hierarchy" and will become a demon when he dies and return "to kill again and again" after possessing someone else.

"You will know my work by my sign, the pentagram will fly again," he wrote, referring to a symbol associated with the occult.

He makes it clear that he idolizes other mass shooters and says he has studied their methods but faults them for not killing more people or for not killing police officers.

He also paints himself as a "loser," with nothing to live for and no successes in life.

"My whole life has been one lonely enterprise. One loss after another. And here I am, 26, with no friends, no job, no girlfriend, a virgin," he wrote.

"But for people like me there is another world, a darker world that welcomes us. For people like us this (is) all that's left," he wrote. "My success in Hell is assured."

The investigative report details how Harper Mercer singled out one student early in the attack and told him it was "his lucky day" because he would be spared if he passed an envelope to police when they arrived.

It held the thumb drive containing Harper Mercer's so-called "manifesto," copies of newspaper articles about other high-profile mass shooters and a report on the killing of children at a Sandy Hook, Connecticut, elementary school.

Laurel Harper told police in an interview the day of the shooting that her son was "born angry" and would have fierce tantrums as a young child that required her to pin him in a "bear hug."

His parents divorced when he was around 2.

As a young child, he opened the door of a car while his mother was driving on a freeway and tried to jump out, she said. He was hospitalized and eventually placed on medications, but he stopped taking the drugs when he turned 18, she said.

His psychiatric diagnosis and other medical information are redacted from the report.

At age 19 or 20, he pointed a gun in his mother's face, she said, and watched videos of killings on a computer in his room. He was kicked out of a U.S. Army boot camp in 2008 for reasons that were also redacted in the report.

Harper Mercer seemed less volatile after they moved in 2013 from California to Roseburg, a small city about 180 miles south of Portland, his mother said.

At one point, as the interview dragged on, officers asked if she needed anything.

She replied, "I think I need my son back. I need to understand, really why he did this. I don't. I'm guessing."