"Looking down people's butt holes isn't in the recruitment video," Senior Deputy John Melville noted dryly.
Silva and the other female deputies rummage through inmates' belongings, looking for contraband.
She yanks up a mattress, running a gloved finger underneath a metal bed frame to feel for razor blades, then leafs through a stack of mail. In the past, she has found greeting cards dipped in methamphetamine and rolls of pot inside letters.
Silva, 35, joined the Sheriff's Department after more than a decade working at an East Los Angeles graphic arts company, selling brochures to car dealerships. Single with no children, she saw law enforcement as an adventure. She said she felt a rush when she went on ride-alongs with sheriff's deputies at the department's Industry station.
"They took the bad guys away," she said.
She looked the jails over carefully before applying to the Sheriff's Department. Tall and athletic, she did not find them intimidating, she said. At first, however, their unnerving reality outstripped her expectations.
"My first three days or so, I was so overwhelmed," she said. "They gave me my keys and radio and told me I would be letting the inmates out. I had to pause for a minute and say, 'Wait, I let them out?' "
Silva soon absorbed the language of the jails, where inmates are "fish," whites are "woods" and transfers who turn up at the North County Correctional Facility when they shouldn't are "stolen bodies."
She saw the ritualized way of life inmates create for themselves, always ordered by race. Pay phones are marked as black or Latino by the way the receiver hangs. Crossing in front of the wrong day room table, onto another group's turf, can trigger a confrontation.
Inmates were happy to talk to her about how and why they committed their crimes. Their claims of innocence, or that drug addiction forced them into desperate acts, often made her less sympathetic, though, not more.
"I don't have compassion for inmates," she said. "They're here because they caused pain to somebody."
For some, the "Groundhog Day" repetition of jail duty saps morale and motivation.
"Custody ruins people," said another deputy at the jail, where he has been stationed for more than five years. "You sit around. You become stagnant. Sometimes you get lazy."
Silva said going on department-sanctioned ride-alongs in her off hours helps combat the sense that she is marking time. She feels a quiet satisfaction, she said, when her part of the jail works as it should.
Tossing Dorm 726 took the better part of an hour.
By the end, knee-high piles of forbidden items cover the floor: loose blades, stashes of extra linen, pictures of women in their underwear, bags of fruit and bread that inmates save to make an alcoholic brew called pruno.
Deputies say they try to search at least one dorm per shift.
Silva looks at the mess.
"Sometimes," she said, "I feel like the cleaning lady."
VIOLENCE is a constant backdrop to Silva's work, so commonplace she no longer gives it much thought.
Her radio buzzes intermittently with traffic about 415s, altercations somewhere in the jail. Most are "inmate only" -- there were 614 inmate-on-inmate assaults at the jail in 2005, more than twice as many as in 2000.
The alerts Silva has come to dread are "deputy involved." Inmate attacks on the jail's staff have almost tripled since 2000 and average about 30 a year. In the summer of 2005, an inmate swung a broom handle, baseball-bat style, into a deputy's head, fracturing his skull.
So far, Silva has been spared. Still, she said, she has learned to see even the most innocuous-looking objects and people as potential threats.
Assaults can inflict as much damage on deputies' psyches as on their bodies.
"It's humiliating," said a deputy who was once drenched in urine hurled by an inmate. "Imagine walking down a row of inmates with excrement running down your face and they're yelling and taunting you. They know they have hepatitis. They know they have AIDS. They aim for an open area -- your nose, your eyes, your mouth."
Deputies can come to see inflicting force of their own as the only way to survive, he added.
"If you scream and run away, they know they've got you," said the deputy, a hulking weightlifter who declined to give his name for publication for fear that his frankness would prompt discipline. "Anybody gasses me, they know they're going to get beat up. Simple as that."
Roger Clark, a retired Los Angeles County sheriff's lieutenant, said it is inevitable that some deputies take this hardened mind-set with them when they become patrol officers.
"When you're in a system for years that dehumanizes, how can you be expected to treat anyone differently when you go to the streets?" he said. "It becomes a muscle memory response."
Knowing that their seemingly controlled surroundings can dissolve into chaos at any moment leaves the jail's staffers tense.