In a working-class neighborhood east of the Los Angeles city limits, Roberto Becerra ducked under the eave of the Spanish-tile roof he recently rebuilt for his mother and stepped into the RV parked in the driveway.

He's been working on the camper for months now. New carpeting. A TV on a swivel. Little houseplants on the bookshelves, tied to the wall so they don't fall over. The thing's got some years on it; the sunset-style paint job screams 1970s. "But it's coming along," he said, brushing his hand along the new drapes.

Becerra's is a thoroughly suburban American life. Sort of.

He's nuts about hockey and Oktoberfest. He works as a foreman on high-end construction sites. He's got a kid on the way, and when he has time he jots a few words in a baby book. When asked to describe his reaction when he learned of the pregnancy, he wrote: "Daddy told every one of his employees."

Look closer, though, and you'll find a curious key chain hanging from a nail on one wall of the house. It's the hand of a skeleton, the fingers contorted to form the letter "F."

There's another "F" next to Becerra's right eye. Another on the hockey jersey he bought his girlfriend recently. Another on the bill of the hard hat he wears at work -- reminders, everywhere, of his allegiance to one of the largest and most confounding gangs in the metropolis: Florencia 13.

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In recent years, Florencia has been subjected to mass arrests and one of the largest federal indictments of a California street gang. The Los Angeles County district attorney's office set aside a prosecutor to exclusively handle homicides committed on Florencia's turf.

Once gangs evolve into full-fledged criminal enterprises, authorities often saddle them with court injunctions that limit their movements and activities. Florencia has three such injunctions.

But according to law enforcement officials and gang members, Florencia has grown ever more powerful and influential, subsuming smaller gangs and staying ahead of the police by diversifying its criminal pursuits.

According to gang members, Florencia now has 46 active "cliques" and as many as 7,000 members.

Other large gangs -- such as 18th Street and Mara Salvatrucha, which rival or exceed Florencia's size -- are composed of loosely affiliated cliques scattered across a wide area. But most of Florencia is clustered in a contiguous area that now includes not just Florence-Firestone, its historical domain, but Huntington Park, Bell, Walnut Park and stretches of South L.A. and Watts.

The cluster is five miles wide and as deep as three miles -- where a single gang is dominant, where kids can often be heard shouting "F-1-3!" That scope presents law enforcement with a daunting challenge, because the gang has become virtually synonymous with the community itself, particularly among Latino men.

"They are so deeply rooted," said Adan Torres, a veteran Los Angeles County sheriff's detective who has devoted much of his career to policing Florencia. "You can't go on any block without encountering one of them. . . . The homeowners are former gangbangers who made it, but now their kids are gangbanging. It's a cycle."

Indeed, many are born into it.

When Sonny Ontiveros was a boy, both of his parents were sent to prison; his father was killed there, and his mother served 15 years for robbery. Ontiveros, now 34 and a father of five who works the graveyard shift as a machine operator, said that he was, in effect, raised by Florencia -- "the only familia I ever had."

Florencia has become both a menacing street gang and a way of life. In that void, there are hundreds of veteranos like Roberto Becerra -- proud, unapologetic members of Florencia, yet seemingly uninvolved in the gang's criminal enterprises.

Becerra is known to all as Flaco, the nickname he has scrawled on the ceiling of his otherwise spotless RV. He lives a content, uncluttered life in an odd netherworld, a 43-year-old man with "TOWN DRUNK" tattooed across his knuckles and two hands clasped in prayer etched on his chest, a gang member with a day job and a business card.

Born in the '50s

Oh, Florence, I love you so

Oh, Florence, be true to me

"Florence," The Paragons, 1957

Borrowing its name from East Florence Avenue, Florencia began in the 1950s as a neighborhood protector near Roosevelt Park, a bustling, diverse enclave of bungalow-style housing built to serve the workers at the nearby factories. It was a time of fedoras and zoot suits, of car clubs and doo-wop music like that Paragons tune, which was adopted as the gang's theme song.

But in the ensuing years, Florencia moved into increasingly serious criminal enterprises, particularly after becoming an ally of the Mexican Mafia, a powerful prison-based "supergang" that shapes much of the state's gang activity.

Authorities say several ranking members of Florencia are also members of the Mexican Mafia. "La Eme," they say, has assisted Florencia's efforts to control the flow of drugs into a sizable chunk of L.A. It has also made Florencia famously disciplined. Members are expected to stay in top physical condition; that way, if they're arrested, they can assist in maintaining control of the prison yards, according to those familiar with the gang.

Florencia works with Latin American cartels to smuggle cocaine, according to federal officials, and recently it became one of the first gangs to introduce the traditionally rural drug methamphetamine into the city's core. Authorities say the gang also does a thriving business in identity theft and is responsible for much of the area's bootleg DVDs.

'I don't claim'

Late one Saturday, police drew their guns and raced to surround a tiny house in South L.A., part of a sweep of suspected Florencia members. Inside, officers found red beans cooking on the stove. On one wall was a needlepoint sign that read: "Love grows happy hearts." They also found Cesar "Demon" Ortiz, 31, an alleged Florencia member with a history of drug, theft and assault charges.

"Who do you claim?" Officer Matt Ensley asked him, street vernacular for asking someone's gang affiliation. "I don't claim," Ortiz said.

Ensley looked under his T-shirt, where the word "FLORENCIA" was tattooed in block letters. "You got it on your stomach!" Ensley said.

"Yeah. But I don't walk around without my shirt on," Ortiz replied sheepishly. He told the officers he'd gone straight since prison, that he was a father now, not a gang member.

"I just got mixed up with the wrong people," Ortiz said.

"But you got the name 'Demon,' " Ensley said.

"I didn't pick it."

"But you had to earn it."

"Yeah."

Sweeps are commonplace in Florencia strongholds -- and enormously controversial.

Major investigations have sent scores of ranking Florencia members to prison in recent years, including a 2007 indictment of 102 men linked to the gang -- an action described at the time by federal officials as "the largest gang takedown in American history."

"We've gotten the main players, the most violent players, out of the game," said Torres, the sheriff's detective. "In 10 years, there is going to be a major difference." In Florencia strongholds, many argue that young Latino men are treated harshly and unfairly -- and that the area needs jobs, better schools and youth programs, not intensive suppression.

The gang, for instance, has long held carwashes to raise money for one another; when somebody dies, the gang often pays for funeral costs. That tradition has faded because the injunctions' strictest provisions prohibit gang members from associating in public. Gang members also contend that the police crackdown has hamstrung them -- leaving them unable to defend and protect their neighborhoods.

One recent afternoon, Rene "Scrappy" Suarez Jr., 22, strolled along Pacific Avenue, in Huntington Park. The stores there are forthright about their clientele. One sells boots adorned with an image of Jesus Malverde, a legendary bandit who has become a folk "saint" among some drug traffickers. When Suarez entered another store and inquired about jeans, the saleswoman -- knowing that most Florencianos wear their pants as baggy as possible -- offered him a size-46 waist for his 32-inch frame.

Suarez said he began selling crack for Florencia at the age of 12, with a Beretta pistol in his waistband. He later became a "gunner" -- "more muscle than hustle," he said -- because it was a "more valuable trade."

More recently, Suarez says he's put the criminal life behind him and has been instrumental in developing an "understanding" between Florencia and 18th Street, a traditional rival -- something the police were never able to do, he is quick to point out.

After leaving one store, Suarez spied a piece of graffiti on a lamppost left by someone from another neighborhood. It was, he said, an affront from an outside gang that would never have occurred if Florencia had been left to its own devices to patrol the neighborhood.

"If there was any illegal business going on in this neighborhood, it was coming from us," he said. "Nobody did anything -- robbing a liquor store, nothing -- without us. It was tightly run, with pride. . . . . If you're going to harm my neighborhood, I'm going to harm you."

'It's who you are'

No matter how much pressure is applied to Florencia, men like Roberto "Flaco" Becerra, who act not as criminals but as elders and mentors, will continue to be the tendons connecting the gang with the community itself.

There is a Flaco, it seems, in every Latino gang in L.A.; it means "skinny" in Spanish. This Flaco was an excellent student, but his interest waned toward the end of high school. He was arrested for the first time as a teenager, for shoplifting magazines, and left school shortly before graduation. The gang -- he calls it "the neighborhood" -- came calling about the same time. He was brought in with a traditional 13-second beating that left him with a busted lip and a broken rib. It was, he said, simply what you did.

"It just happens," he said. "It's just your neighborhood. It's who you are."

His parallel lives began.

He began working on construction sites and was soon asked to run portions of the jobs. Today he is something akin to a superintendent, with 20 employees on several sites, most in the Hollywood area.

These are long-term assignments. He's been on one job site for four years; his first day there he directed traffic on Sunset Boulevard while the demolition crews pulled in. More recently he took a set of promotional photos himself, showing the development's ocean views.

"From the ground up," Becerra said as he inspected a couple of new units on a recent afternoon. He has an eye for detail; on the way out of one unit, he examined a banister and realized that it would not be acceptable to the developer because it was too close to the edge of the stairs. Someone could pinch a hand walking down the stairs, he said, so the banister would have to be moved.

"It's fun," he said of his job. "The day goes quickly when you like what you're doing."

At the same time that his career has moved forward, he has had bullets scrape the back of his head, leaving a line along his scalp.

"I was lucky," he said. "I just never got hit."

He is entrusted to hand out paychecks to his employees on Fridays -- and entrusted to count the 13 seconds when a new member is "courted" into the gang with a beating: "One one thousand, two one thousand . . . "

"I got a brain. I came from a good family. My main priority in life is to take care of my family," he said. "But my neighborhood is with me too. And it's never going to go away. Never."