Seven years after the Golden State Killer was finally caught, a new book is giving a behind-the-scenes look at the investigation.

Sacramento County District Attorney Thien Ho, the prosecutor who put Joseph DeAngelo behind bars, is releasing his account of working on the case in the book "The People vs. The Golden State Killer."

On Wednesday night, more than 300 people, including some survivors, packed Sacramento's downtown library for a book signing and a conversation about one of the state's most notorious cases.

"You're talking about one of the most prolific serial killers in our country's history," Ho told CBS News Sacramento at the book signing.

Ho was a lead prosecutor on the 2020 trial that resulted in DeAngelo admitting he committed the murders, rapes and other crimes associated with the man who was known across the Sacramento region as the Golden State Killer and the East Area Rapist. His book gives details on the decades-long effort to track down the suspect and describes what happened once he was finally caught.

"One of the things that we talk about for the first time is really his interrogation," Ho said. "That's never been discussed publicly before."

The crimes began in the 1970s and stretched across the state, with DeAngelo wearing a mask while sneaking into homes at night and tying up victims at gunpoint.

"You talk to anybody who had lived in Sacramento at that time, they all remember the East Area Rapist," said Carol Daly, a retired East Area Rapist detective and undersheriff. "They all remember the fears going on."

"I wanted to focus this book really on the generation of law enforcement officers that never gave up the search for him and on the victims and survivors who found their voices," Ho said.

Some of those survivors were on hand for the book's unveiling.

"I think having my story available for people to read is of utmost importance," said survivor Kris Pedretti. "Victims are going to read this and they're going to say, 'if she was able to tell her story, maybe I can, too.' "

Ho said he felt it was important to document the decades of work that went into the investigation, which led to a man who once worked as a police officer and who remained living in the community with a wife and kids.

"Really go into the mind of a monster and pull the mask away from this monster and see what's really underneath," he said.

A portion of the book's proceeds is going to the local nonprofit group Phyllis's Garden, which was founded by a victim and provides support for survivors of sexual assault.