I had never snitched in my life. In my youth, I had been counseled by friends never to catch the eye of a police officer and to be very wary in their company. Later, as someone whose face had been on the cover of Life magazine as a leader of the so-called “other culture,” I was doubly suspicious of the police. In writing and researching the book, however, I began to feel sympathy and respect for a number of police officers whose work I began to understand and appreciate.

So I decided to go to the authorities. I contacted a CBS reporter who was covering the trial and told him what I knew. Together we made arrangements to tip off the police.

The weekend before the trial began, I learned that Manson had been moved to a super secure cell at the Hall of Justice, the same place he was to be tried. The cell had previously held Sirhan Sirhan , the man prosecuted for the assassination of Robert F. Kennedy.

Fear Swept the Poolsides

There was great fear of Manson and his disciples, at least in Los Angeles during the trial, among those associated with movies and the music business. One need look no further for the origins of our abiding fixation: Many of the culture’s prominent voices from the past 50 years were shaped by that fear, their worldviews and obsessions forged in it. (In a recent interview with Esquire, Tarantino, who grew up in Los Angeles and was 6-years-old at the time, called 1969 “the year that formed me.”)

I saw that fear at work firsthand. Whenever my band played Los Angeles in the 1960s, we stayed at Sandy Koufax’s Tropicana Motel, located on Santa Monica Boulevard near La Cienega. There was a banana tree by the pool and hibiscus bushes with large red flowers. And there was always a party. During the summer of 1970, while I attended the Tate-LaBianca trial, I stayed with my wife, Miriam, and ­5-year-old daughter, Deirdre, at the Tropicana.

Others in the music business were also staying at the Tropicana that summer, including Kris Kristofferson, the 5th Dimension and Janis Joplin, who was cutting her final album, “Pearl.” In the afternoons, the tables by the pool would fill up with visiting friends, including Phil Ochs, the writer John Carpenter and the singer Rita Coolidge.