The months-long offensive, the fruit of dozens of federal investigations over three and a half years, will put a significant dent in the U.S. operations of La Familia Michoacana, one of Mexico's fastest growing and deadliest cartels, authorities said. 'The sheer level and depravity of violence that this cartel has exhibited far exceeds what we unfortunately have become accustomed to from other cartels, (and) the toxic reach of its operations extends to nearly every state within our own country,' Attorney General Eric H. Holder Jr. said at a news conference in Washington to announce the arrests. The investigation has involved hundreds of agents and analysts from the FBI; the Drug Enforcement Administration; and the Bureau of Alcohol, Tobacco, Firearms and Explosives, as well as prosecutors and other officials from the Justice Department. 'We're hitting them where we believe it hurts the most: their revenue stream,' Holder said. 'By seizing their drugs and upending their supply chains, we have disrupted their business-as-usual state of operations.' In all, authorities have arrested nearly 1,200 suspected La Familia members or associates in recent months as part of 'Project Coronado,' the multi-agency effort to dismantle the organization's methamphetamine and cocaine distribution network in the United States. But Holder and other officials conceded that La Familia has become too powerful, too politically entrenched -- and too popular with Mexico's citizens -- for the arrests to deal the cartel any kind of death blow. 'We have to work with our Mexican counterparts to really cut off the heads of these snakes and get at the heads of the cartels ... either in Mexico or extradite them to the United States,' Holder said. For that to happen, U.S. authorities need the full cooperation of the Mexican government in arresting and prosecuting the leaders of La Familia. But according to court documents unsealed Thursday, few if any leaders have been taken into custody by Mexican authorities, despite several being indicted in U.S. courts. La Familia has been linked to hundreds of drug-related killings in Mexico, including the kidnapping, torture and murders of 12 federal agents in the western state of Michoacan, La Familia's home base. Several senior U.S. drug officials said Mexico is cooperating, but that La Familia's leaders are too well-insulated to go after, protected not only by their own private army but also by corrupt local police and politicians. 'It's a full-blown military operation to go in and get them,' said one drug enforcement official, speaking on the condition of anonymity due to the sensitivity of U.S.-Mexico counter-narcotics relations. A Mexican counter-narcotics official agreed, saying his country has thrown thousands of troops and police at La Familia, but the cartel's chieftains are even more elusive than others. 'They rarely spend two or three nights in the same place, and when they do, they live in these very fortified compounds,' said the official, who also spoke on the condition of anonymity citing similar sensitivities. 'It is even more difficult for us because they buy not only information, but they buy protection from the very guys that are supposed to get them.' Although a relative newcomer to Mexico's drug underworld, La Familia has quickly become one of the most violent, quick to attack Mexican troops and lawmakers who have tried to halt its expansion, U.S. counter-narcotics officials said. La Familia now competes with the established Gulf and Sinaloa cartels. But in an unusual twist, its leaders espouse a religious philosophy, asking core members to carry bibles and attend church. The cartel manufactures tons of methamphetamine strictly for export to the United States, prohibiting their own soldiers from using illegal drugs or selling them in Mexico, said Michele Leonhart, acting administrator of the Drug Enforcement Administration. Such tactics have made La Familia something of a Robin Hood-type organization within Mexico, several drug enforcement officials said Thursday. 'We are fighting an organization whose brutal violence is driven by so-called divine justice,' Leonhart said. 'Accordingly, La Familia's narco-banner declared that they don't kill for money and they don't kill innocent people. However, their delivery of that message was accompanied by five severed heads rolled onto a dance floor in Uruapan, Mexico.' The indictments unsealed Thursday provided a rare look inside the highly disciplined and secretive organization, which is also involved in counterfeiting, extortion, prostitution and armed robbery. Most of those arrested in the United States were believed to be foot-soldiers or associates of the organization, but some of them have direct ties to La Familia leadership in Michoacan, authorities said. Federal prosecutors in Los Angeles have indicted five suspected La Familia members with the help of several undercover informants. One of the indicted is Gerardo Rodriguez-Lopez, a fugitive who authorities allege ran a methamphetamine smuggling operation from Mexico through Los Angeles County to Minnesota, Kansas, Georgia and Texas. Overall, the DEA said at least 24 individuals were arrested in Southern California during the latest raids, many of them La Familia members or associates from three separate drug distribution cells. Over the past two days, federal and local authorities arrested 90 people in Dallas and dozens more in Atlanta and other large urban hubs for La Familia. But many other arrests occurred in small towns and rural communities in Washington state, Texas, California, Oklahoma, Missouri, North Carolina and elsewhere. Times staff writers Tracy Wilkinson in Mexico City, Sam Quinones in San Bernardino, Calif., and Richard Winton in Los Angeles contributed to this report. 