If there is a man alive who understands the heart, mind, and soul of police officers and has the ability to write about them with eloquent simplicity, horror, and humor, illustrating their terrible truths and wondrous joys, it is Joseph Wambaugh.

He was a cop for 15 years, finally forced to resign because his books were so successful that he had become a celebrity. Bad guys wanted their pictures taken with him and asked for his autograph. Other cops resented the fame and, oh, yes, the money, that rained down on their sergeant, not to mention the distraction of relentless calls at work from Hollywood people — producers, agents, script writers, actors and actresses — who wanted a bit of him.

He had stories enough to fill a steamer trunk, drawing on his own experiences and those of fellow cops, and he knew how to write them.

The books, beginning with “The New Centurions” in 1970, created a new genre, the cop novel, which had nothing to do with all the other books involving policemen that had been written before. Mr. Wambaugh’s tales are about the lives of cops, both on the job and off, and it is abundantly clear that they live lives that are more colorful than Elton John’s laundry.

Because of the tremendous success of “Hollywood Station,” Mr. Wambaugh’s early books are being re-issued, and what a boon this is, both for new readers and those who haven’t been able to find copies of his books for a while.

“The New Centurions” (Grand Central, 481 pages, $7.99), the stunning first novel, comes with a new introduction by Michael Connelly and a bonus first chapter from “Hollywood Crows,” Mr. Wambaugh’s new novel, also just released and on the top of my pile of must-reads.

“The New Centurions” follows three very young, mostly scared but dedicated men who are recruits in the LAPD in 1960. Getting through the training is pretty tough, but so are the streets of the City of Angels, as they are to learn all too quickly, especially toward the book’s conclusion, set at the time of the Watts riots — the perfect, if extreme, symbol of the chaos of a world in which it is their duty to maintain order.

The author’s second book is “The Blue Knight” (Grand Central, 356 pages, $7.99), which also features the first chapter of “Hollywood Crows” and the same introduction by Mr. Connelly, who has joined Mr. Wambaugh as the ace practitioner of Los Angeles police novels.

This poignant story is about William “Bumper” Morgan, a 20-year veteran of the department who is two days short of retirement when he finds himself in a terrible situation. Morgan believes he knows what’s best for the people he has sworn to protect, and he does whatever is necessary to fulfill his oath. His view of the law is that it is designed to prevent him from adequately doing his job, and he often acts more courageously than intelligently.

James Ellroy wrote a new introduction to “The Choirboys” (Delta, 399 pages, $13), the most hilarious of all Mr. Wambaugh’s books, yet one of the darkest, which tells of a group of cops who meet off-duty to drink, vent, weep, rage, and carouse in MacArthur Park. The inhumanity their job forces them to witness affects each of them differently, and the juxtaposition of the cops’ methods of coping with the horror of the job, careening from laughter to violence, is chilling in its apparent authenticity.

Let me warn you about his third book, “The Onion Field” (Delta, 492 pages, $13). It is too good. No, I’m not joking. It is a true story of two cops who are surprised by a couple of punks who disarm them, kidnap them, and eventually kill one of them while his partner escapes through a dark nighttime onion field, but into a life of guilt, nightmares, impotence, and insanity. The tragedy of Karl Hettinger and a criminal system that not only made life hell for cops but actually favored the criminals is shown with all the outrage that the author could muster, and all the sadness for the cop who became its prime victim.

This edition features a new introduction by Mr. Ellroy, which recounts the importance that Mr. Wambaugh, and especially this book, had on his life, indirectly sending him to sobriety and a career as one of America’s most influential novelists.

The warning? “The Onion Field” will haunt you forever, as it has me.

Mr. Penzler is the proprietor of the Mysterious Bookshop in Manhattan and the series editor of the annual Best American Mystery Stories. He can be reached at ottopenzler@mysteriousbookshop.com.