WHEN MY CITY EDITOR yelled out that she needed someone to help cover a shooting at the County General Hospital in East Los Angeles, I sunk low behind my computer, trying to be invisible. As a young metro reporter focusing on transportation back in 1993, I had barely typed a word about violent crime.

Forty minutes later, I lingered near one of the hospital’s side entrances, unable to spot any fellow journalists milling around. So, I popped open the door, figuring they might be inside. That’s when a tubby police officer whipped around the corner, telling me in an angry whisper that the gunman who’d already shot three doctors — one with a .38-caliber slug to the head — was holding two people hostage just around the bend. “Get down and go!” he said, his hand gripping a revolver.

I left, lucky only to have been chastised, and discovered the media scrum in an adjacent parking lot. It was now your basic hurry-up-and-wait while authorities tried to end the standoff with the gunman, a disgruntled patient who lived on Skid Row. They hauled him off in a squad car after several hours, and as I angled for a view of his face, an overly aggressive TV cameraman whacked me in the back of the head with his lens. But I still noticed the suspect resembled Richard Ramirez, the “Night Stalker” serial killer who had terrorized Los Angeles the previous decade.

By nightfall, with our story for the San Gabriel Valley Tribune in editing, I needed to decompress. I ripped off my nicotine patch and bought the last pack of cigarettes I’d ever smoke.

The O. J. Simpson murders would be the next crime story I’d write about, if tangentially, for the Los Angeles Times and its rival, the Los Angeles Daily News. Full-time crime reporters, as I learned, were the characters in the newsroom, often cynical, swashbuckling, and as brash as the cops with whom they interacted. I didn’t run in that herd.

It wasn’t until one day in 1998, strolling along Hollywood Boulevard, that I got stopped on the sidewalk by a guy named Jerry Schneiderman who had been both a source for stories and a bit of a fabulist.

“Did you know,” he said, “that I once had a double murderer chasing me?”

He claimed the ordeal ruined the “old” him, gutting his first marriage and leaving him forever mistrustful of strangers.

Yeah, right, I said, figuring he was either pulling my chain, as he was apt to do, or exaggerating something unverifiable.

Never was I more wrong.

Schneiderman had been a nerdy 27-year-old space-planning prodigy when his partner, a suave, charismatic fellow 12 years his senior, persuaded him into something of a real estate get-rich-quick scheme: adding construction services to their otherwise white-collar business sketching interior blueprints for Los Angeles companies big and small. In need of an experienced foreman — and a California contractor’s license — they hired a quiet, windburned applicant, sight unseen. What Schneiderman didn’t know was that both his colleagues bore secrets, one more diabolical than the other. From the ashes of financial misconduct and palace intrigue soon emerged a sequence of events out of an Elmore Leonard novel.

Then again, life in 1979 Los Angeles made for plenty of deadbolted doors and just as much paranoia. Murder rates were spiking. “White flight” was growing, as were gated communities and racial tensions between people of color and the increasingly militarized LAPD. Worse, overlapping serial killers (like “The Hillside Strangler” and “The Freeway Killer”) seemed to prowl at their leisure.

Beyond the criminality, Southern California exuded this seething aura, just like the rest of a demoralized post-Vietnam, post-Watergate United States, except amid palm trees and famous boulevards. The anchor’s rant in Paddy Chayefsky’s brilliant Network, where he encouraged viewers to scream that they were “mad as hell,” felt less Hollywood drama than modern documentary. There was a noir quality to our existence that rendered even our beloved La Brea Tar Pits a shadowy expanse you didn’t want to hang around at night. A 17-year-old at the time, what I remember now are the gloomy skies and sullen adults.

Years later, I realized that Schneiderman only had a keyhole-wide understanding of the darkness that had swirled around him. For instance, he had little understanding that his partner’s execution with a powerful World War II–era rifle represented the opening salvo in a boutique murder-for-profit corporation. The ringleader of it was Howard Garrett, their vulture-faced foreman who’d decided to toss caution to the wind by cashing in on other people’s demises. In a tense meeting where Garrett blackmailed Schneiderman, threatening him and his family with their own murder contracts, Garrett warned Schneiderman that he had killed before “and gotten away with it.” He wasn’t lying.

The web of would-be assassins that ensnared Schneiderman included a bantam-sized gunman with a deadeye aim, a transgender thief, and a bisexual white supremacist crook with a grain of conscience.

But I never could’ve unearthed a drop of this 20-year-old saga without my journalism background. As such, I spent hours in the Hall of Records’s dungeon-esque basement in downtown Los Angeles, examining court filings, even though many were missing or stolen. I interviewed dozens of people swept up in Garrett’s months-long reign of terror, among them former LAPD homicide detectives who, like Schneiderman, couldn’t forget Garrett. Eventually, I connected with the lead prosecutor, who offered public documents that confirmed the outlines of this weirder-than-fiction tale.

One salacious document showed that between the time when Schneiderman’s business partner was murdered and Garrett was dramatically arrested he worked on a freelance construction job at the offices of the California Association of Realtors, a trade group promoting integrity in the real estate business.

All of this digging kept me at a comfortable distance from the actual villains involved. I still craved to learn more, and with Garrett long dead, there was only one person who knew the truth about him: the triggerman who’d fired the fateful bullet into the head of Schneiderman’s feather-haired partner, Richard Kasparov.

Johnny Williams was many things: a bushy-haired man who had already admitted to killing multiple people before this, an industrious criminal alchemist, and the victim of a traumatic brain injury from tumbling out of a moving car. That pivotal event had demented him from a kid with a soaring IQ into a sociopath.

To hear him out, I typed up a letter requesting an interview, and then, probably a dozen times, stuck it in my mailbox only to retract it moments later. Williams had testified under oath, to a stupefied courtroom, that killing to him was no big deal. Years later, the parole board at Corcoran State Prison in Central California repeatedly denied his release, deeming him an ongoing threat to society.

What if my nosy questions about what landed him behind bars incensed him and he was subsequently freed? Even the internet of the early aughts made it simple to locate someone’s address. Would he pop up outside my window with a big gun, just as he had with Schneiderman’s partner, for one last slaughter? What about my family? Were Williams’s sinister memories worth it?

That one-page letter collected dust in my file cabinet for two years as I hemmed and hawed, weighing the risk, when I heard that Williams died behind bars.

Then I wrote The Darkest Glare, a nonfiction account that tried to stitch all the craziness together into a single book. I hope I did it justice without Williams.

I was confident I could handle not only the Kafkaesque twists of Schneiderman’s ordeal but also the prologue of it — the PTSD, the legal and emotional dominoes that cascaded afterward, the questions about hidden identities behind the smiles of Los Angeles contractors. And that’s all because a distracted city editor shooed me out the door to cover that hospital shooting. The best story is the one you never set out to write.