DENVER — We are learning more about the man accused of murdering nine people inside a Charleston church.

Former classmates of 21-year-old Dylann Roof said he was a loner, abused prescription drugs, and actively told people about his hatred for certain groups.

Stephen and Joyce Singular, the local authors of the book, “The Spiral Notebook, the Aurora Theater Shooter, and the Epidemic of Mass Violence Committed by American Youth,” said those traits are a common theme in people who commit mass violence.

Witnesses said Roof sat with the congregation for an hour before the mass killing.He may have even prayed with them.

“Imagine the control you have to have over yourself to sit with people for an hour after you do that. And then leaving a victim alive to tell the story. I mean it’s so cold-blooded, so cold-hearted,” Joyce said.

The Singular’s have studied mass violence and the youth who commit it for years.

They said what we are learning about Roof fits the profile, nearly to a tee.

“In a number of cases, not all, but you’re talking about people who are relatively well off, have educational opportunities. That`s the community it’s coming from … Young white men,” said Stephen.

In fact, according to an excerpt from their newest book, the authors note that nearly 80% of mass shooters are white males. Most are loners and most have embraced violence in their everyday lives.

The same description former classmates used for Roof.

“This theme of young males, not wanting to appear weak, not wanting to seek mental health help, wanting to be like an action hero in a video game or movie and it`s a very corrosive and dangerous mindset,” said Stephen.

The Singulars say it’s possible, like in other cases, cries for help went unnoticed and now something needs to be done.

“These are major social crimes. I think they killers are trying to make a social statement. And I think the fundamental social statement is I don`t know how to cope with myself, I don`t know how to cope in this society and I`m going to do something so outrageous that people are going to know that about me,” Stephen said.

The authors said they wrote this book because it’s time to take a proactive look at what we can do to help people like Roof who are obviously very troubled and dangerous, in the hopes that we can prevent killings like this in the future.