A few months earlier, Longacre—a Winston-puffing, Budweiser-drinking 35-year veteran of the LAPD—had been assigned to look into a rash of burglaries in the well-to-do neighborhoods of the San Fernando Valley and the Mulholland corridor that runs through the mansion-studded hills overlooking Los Angeles. With little to go on, the detective reverted to basics. He plugged information from about 40 cases into a 20-column grid. Patterns emerged: daytime crimes, rear and side entry, second-story entry. Longacre had a modus operandi and an area of operation. Now he needed a face and a name.

In the locker, Longacre also found gold- and gem-testing kits, books on alarm bypassing and safecracking, and a USB drive. On it, the as-yet-unknown thief had saved several Photoshopped IDs. The cards had dummy names, but the images were real. The detective spent three days combing through mug shots in a police database. Bleary-eyed, he found one that seemed to match the photos on the USB drive. The man in the picture was booked under the name John Matthew Emerson. The mug shot was taken in 2000 after a shoplifting arrest in West Hollywood. Before he'd begun his burglary career, Del Río had been caught pinching small items like MET-Rx packets from stores. Emerson was one of the aliases he used. It was the one that made it into the database. Longacre forwarded the image to police divisions in the Valley. He was counting on the thief to keep stealing.

Del Río did just that, upping his burglary count throughout January 2006. What's more, he was so outraged that the cops had emptied his locker that he hired lawyers to call Longacre and demand the return of his property. Del Río's mercurial personality—brooding one moment, manic the next—had been on display before. He'd been booted from a gym in Los Angeles for kicking an owner during an argument. Later he would tell people he was bipolar.

At some point, the disgruntled burglar slipped through a fence near a Mormon church in Granada Hills. He carried a two-foot-long piece of black plastic pipe and a shovel. Inside the pipe was his haul for the month, an estimated $500,000 worth of cash and jewels. A few steps into the wild sunflowers, Del Río began to dig a hole. He had chosen this hiding spot well. The power lines overhead generated an electrical field that disrupted metal detectors.

THE DEL RÍO WHO ENTERS THE HOUSE IN ENCINO—HIS FOURTH JOB OF THE day—on February 16, 2006, is far less meticulous. The home is a difficult target: There's only one exit off the property and only one road out of the neighborhood. A single mistake will leave him trapped. With his screwdriver, he opens a window and slips inside, then foolishly ignores one of his own rules: Check every room. He fails to notice the live-in maid waking up from her nap. The police quickly respond to a call from the homeowners, and four officers bear down on the property with guns drawn. Del Río sees them as he's climbing through a rear window and reverses course, running out the front door. There's no escape. Cornered, he drops to his knees in the driveway and says, "I give up."

For cat burglars, there's no thrill without a challenge. No real reward. But the frequency and heightened risk of Del Río's thievery in 2006, the uncharacteristic carelessness, suggest a subliminal motive. After the storage-space breach, he knew Longacre was after him. But he continued to prey on the same neighborhoods. "Some crooks want to be caught," says the detective. "That's their way of stopping their antisocial behavior."

When Del Río is booked, he gives the name Roberto Caveda, an alias with a sentimental appeal—Calle Caveda is the street Del Río 's brother lives on. It's in Gijón, where the master criminal first put his toe on the wrong path. A detective who'd seen Longacre's photos immediately recognizes Del Río 's face.

Hours later, Del Río yanks out the drawstring of his shorts and ties his socks to it, hooking the makeshift noose around a sprinkler head in the ceiling of his holding cell. By the time the guards get to him, the sprinkler has flooded the station. He attempts suicide twice more in the months ahead. In lockup at the Van Nuys courthouse, he garrotes himself with his pants and nearly dies.

Because Del Río attempted to kill himself several times while in custody,
he was restricted from shaving or cutting his hair. He refused to eat prison food
and lost 25 pounds.