There are two ways to get a piece of the action at any of the big drug markets along the border: pay off — or kill off — anyone who stands in your way. But to gain exclusive control of the most lucrative gateway of all, says a veteran U.S. drug cop, a drug cartel has to pay and kill " beyond where any have ever gone before."

And so few boundaries — national, moral, legal — constrain the border's worst bad guys: Benjamín Arellano Félix, 49, and his kid brother Ramón, 36. The two baby-faced playboys head the Tijuana cartel, which sits atop Mexico's $30 billion drug-trafficking underworld and may be the most powerful organization in the country of any kind. Each year they smuggle to the U.S. hundreds of tons of cocaine, plus marijuana, heroin and methamphetamine, ferried on ships, on planes and inside truckloads of legitimate merchandise. The Arellanos are thought to have hundreds of millions of dollars stashed away, and that's after bribing Mexican officials, cops and generals to the tune of some $75 million a year.

As for murder, it has evolved from the cartel's last-ditch way to protect market share into its preferred means of communication. " [Druglords] rule by terror," says Errol Chavez, special agent in charge of the U.S. Drug Enforcement Administration's San Diego office. According to testimony from former associates, Ramón often rises in the morning announcing, "I feel like killing somebody today," then satisfies the urge in ways designed to build the legend, feed the fear. Trademarks include "the Colombian necktie" — cutting an informant's throat below the chin, then pulling his tongue through the wound as he bleeds to death. Or suffocating a rival with a clear plastic bag over his head while a henchman named El Gordo (the Fat Man) bounces on his chest. But perhaps Ramón's favorite ritual is carne asada — barbecue — executing entire families and tossing their corpses on a bed of flaming tires, as he and his goons celebrate with tequila and cocaine.

But if the Arellanos have a weakness, it may be their failure to see that even the border's notorious criminal culture eventually has its limits. It's true that since the Wild West days, when Billy the Kid wintered in El Paso and Juárez, border natives have often been a law unto themselves — a product of their historic, and justified, resentment of racist gringos to the north and haughty chilangos (Mexico City residents) to the south, who sneered at the border for being neither American nor Mexican enough. "That identity crisis and alienation grew into the violent face of the border," says sociologist Juan Manuel Valenzuela of Tijuana's Colegio de la Frontera Norte. Coupled with the region's poverty, it spawned a subculture of toughs, often called pachucos and cholos.

Though the Arellanos are the heirs to that world, they are also a ghastly mutation. Their uncle Miguel Angel Félix Gallardo, an ex-cop from the violent Pacific Coast state of Sinaloa, was the first Mexican drug capo to link up with Colombia's cocaine cartels in the 1980s. He and other druglords shared the Tijuana corridor, but after they savagely murdered DEA agent Enrique Camarena in 1985, in league with senior police and political figures, Mexican authorities put them in jail. Into Tijuana roared the seven Arellano brothers, including the handsome Benjamín, their CEO; chubby Ramón, the enforcer; finance-whiz Eduardo, 44, the money launderer; and the eldest, Francisco, 51, the gregarious, cross-dressing pitchman who, say officials, cemented the clan's top-drawer political and police alliances, usually out of his Mazatlán discothêque, Frankie O's.

Via a multimillion-dollar monthly graft payroll and a string of chilling murders — including that of a key rival's wife, whose head was reportedly severed and delivered in a box of dry ice — the Arellanos realized their audacious goal: to own the coveted stretch of desert from Tijuana to Mexicali. During a 1992 summit of Mexican druglords at a Sinaloa ranch, they raised the fees charged to others for using their turf. In response, rival druglord Joaquín (Chapo) Guzmán sent gunmen to kill the Arellanos at a Puerto Vallarta disco. As bullets rained, the brothers escaped through a bathroom skylight (after struggling to shove Ramón through it). To retaliate, they targeted Chapo the following year at the Guadalajara airport — and mistakenly killed Cardinal Juan Jesús Posadas Ocampo, who arrived in a car similar to Chapo's.

For a time, it looked as if the Arellanos had gone over the line. But after offering confession and begging forgiveness in a secret meeting with the papal nuncio, they simply stepped up the violence. They recruited hardened gang members from San Diego, as well as the bored sons of affluent Tijuana families — a trigger-happy cadre known as "los narco-juniors." Mexican ex-military and police officers filled out their ranks of assassins and helped train new members. They imported not only guns but also heavy weapons from U.S. arms traffickers (they once threatened to fire rocket-propelled grenades at U.S. drug czar Barry McCaffrey during a border visit) and assembled enough state-of-the-art surveillance equipment to know when even the lowliest dope trafficker is cutting a free-lance deal on his cell phone.