It's mid-December in Southern California, and the weather is exactly what you'd envision—sunny, warm, perfect. The sky is suffused with the hazy sunshine that filmmakers prize, light that casts a glow of warmth and generosity over everything. It's the kind of day in which crime seems unimaginable.

"The trap that everyone falls into is that somehow the darkness of human nature and the brightness of the California sunshine cannot co-exist," crime writer T. Jefferson Parker tells me as we eat sandwiches and drink Snapple in his backyard overlooking Fallbrook, the "Avocado Capital of the World," about an hour north of San Diego. "Maybe people want to believe that given a perfect climate the human soul could escalate beyond crime. But it just doesn't happen."

It certainly doesn't happen in Parker's fictional world. His 13 novels—the most recent is The Fallen, out in March from Morrow—are all set in Southern California, which Parker knows intimately. Born in Los Angeles in 1954, he grew up in the Orange County suburb of Tustin, and refers to the region as his "literary home." In the 1950s and 1960s, Orange Country underwent a transformation, from orange groves to suburbs and shopping malls. "The rapidity of the change really made an impression on me," says Parker.

His last novel, the Edgar Award—winning California Girl (Morrow, 2004), deals explicitly with that change, juxtaposing the Orange County of the 1950s with that of the pivotal year of 1968. There's a crime at the center of the plot, but like all of his best work, California Girl is so deeply human that it cannot be easily pigeon-holed as a genre novel. Though Parker readily embraces his métier as a crime novelist, it's clear that engaging the reader emotionally is as important to him as creating a compelling plot. "I defy you to read one of my books and not have some kind of emotional reaction to it, to feel that this matters," he says. "It may not matter a lot, it's not going to change the course of the world, but it's going to mean something during the time you're reading if it's done right."

Indeed, the desire to elicit a response from the reader—the kind of response he had to the writers who made an impression on him—is what drove Parker to write fiction. "I'd always loved stories," he says, "and writers like Dickens and Steinbeck, and thought how wonderful it would be to write book that would give someone one-millionth of the delight those books gave me." He studied English at the University of California, Irvine, and wrote his first novel after college, while working as reporter at a weekly newspaper in Newport Beach. He sent the manuscript to Morgan Entrekin, who told him, essentially, that no one's going to publish a coming-of-age novel about surfers growing up in Newport Beach. "But he also said to me you seem to have some talent; you ought to try to write something more commercial."

And that's exactly what Parker did. He decided to write a crime novel, and began by reading "what my buddies were reading, these wonderful pulp fiction books: Raymond Chandler, John D. MacDonald, Ross Macdonald, Dashiell Hammett." The result was Laguna Heat (St. Martin's, 1985), which got a fine review in the L.A. Timesat a particularly opportune moment: the day he was fired from his job as a technical editor on a defense project. And Parker has never looked back.

To Parker, crime fiction is not merely commercial: "It's big stuff, Old Testament stuff: murder, betrayal, incest, revenge." And he strives to transcend the genre by subverting the tropes of crime fiction: "When I sat down to write Laguna Heat,for example, the world tells me I should be telling this story in the first person. But the reactionary, stubborn part of me said 'I'm going to tell it in the third person.' "

But what really distinguishes Parker's books from many other crime novels is the depth of feeling he has for his characters, particularly his modest, thoughtful heroes, like Tim Hess, a semi-retired police veteran in one of his finest books, The Blue Hour, or Robbie Brownlaw, the San Diego homicide detective in The Fallen. They are Boy Scouts in a sense—earnest, hardworking, essentially good—and, most appealingly, they are acutely aware of their imperfections. They're not as brilliant as Sherlock Holmes and they aren't introspective loners like Ian Rankin's Inspector John Rebus or Michael Connelly's Harry Bosch. They are people struggling with difficult, challenging cases and, often, with difficult, challenging losses of their own.

Hess's three marriages have failed, and he's dealing with a cancer that may or may not kill him. For Brownlaw, his beloved wife, Gina, leaves him just as he gets started on a challenging murder case—and he suffers from an unusual neurological condition that literally changes his outlook on everything. After surviving a serious fall, Brownlaw experiences synesthesia: the jumbling up of senses (he sees colored shapes when people talk).

Indeed, a number of Parker's characters have brain-related injuries, and his interest in them stems from his own personal tragedy: his first wife died of a brain tumor in 1992. "I watched her mind change as the tumor grew," he says, "and that got me interested in how the brain works and the idea that almost anything can happen in the human mind."

Perhaps the losses in his own life—the transformation of the idyllic California of his youth to a land of affluent suburban sprawl, the much more painful loss of his first wife—furnish the themes of Parker's novels. But it's clear that he absolutely adores the challenge of writing. "It's just damn fun," he says. "It's hard work, and when it's going poorly it's no fun. But to write a good sentence... a good passage... a good chapter... all the way up to a good book... that feels good."

Clearly, Parker is enjoying his life as a writer; in fact, he seems to enjoy life in general. He remarried several years ago, and moved south, to Fallbrook, where he and his wife are raising two young children. The relocation has also resulted in a change of setting for his books; Cold Pursuit(Hyperion, 2004) and The Fallen are both set in San Diego, and he has just finished the first draft of a new novel, one with new characters, set in the town of Fallbrook, and involving "everything from drug running to rainmaking." It will also almost surely involve people that readers care about and a plot that keeps them reading.