WASHINGTON — Using drug and racketeering statutes and extradition agreements, federal prosecutors are sending a steady parade of Mexican drug lords into U.S. prisons. While that is having a chilling effect on the smuggling cartels, there is no sign that the convictions are breaking the organizations, which are growing ever more violent, according to U.S. officials and other experts.

Ten cartel leaders from Mexico have been convicted in U.S. courts in the last two years, while another three in Chicago and a fourth in Brooklyn have been indicted in major drug racketeering operations involving tons of heroin, cocaine and marijuana.

In the last few weeks in San Diego alone, four cartel figures were convicted of leading organizations that smuggled tons of the drugs into the U.S., carried out murders and assassinations, and spent millions of dollars bribing Mexican authorities. The men were given sentences ranging from 30 years to life in prison with no chance of parole.

It was hoped that the prospect of U.S. prison time would begin deterring drug violence along the border. U.S. officials say it is having some effect, citing drug lords still at large who admit to being frightened at the prospect of extradition to the U.S. They also say the tactic disrupts the cartels’ activities.

But authorities on both sides of the Southwest border acknowledge that the cartels have simply promoted lieutenants to the vacant leadership positions and that the violence, especially in the last two years, has turned even uglier — in the streets and within the cartels where junior members are fighting one another for control.

“”In Mexico, there are hundreds of thousands of young men who are in organized crime and are … ready to step up when a leader at any level is captured and taken prisoner,”” saidTony Payan, a political science professor at the University of Texas-El Paso, who for a decade has studied border violence.

“”While it is good to catch one of these guys, in the end it’s a little like winning a battle even if you’re losing the war. To me it’s a little bit like tilting at windmills.””

R. Gil Kerlikowske, director of the White House Office of National Drug Control Policy, agreed in a separate interview that the convictions are not breaking the cartels. “”I don’t think there’s any doubt there are people who will replace those folks,”” he said. “”But it is the disruption of the cartels that is helpful, and the chilling effect it causes.””

Justice Department spokeswomanLaura Sweeneysaid the convictions have helped federal agents and prosecutors gather valuable intelligence on the inner workings of the cartels. She added: “”The strongest message we send is the one sent jointly by Mexico and the United States each and every time an individual is extradited to either country to face justice, leaving no safe haven on either side of our border.””

The U.S. prosecutions are having some effect. Earlier this month,Ismael Zambada, known as “”El Mayo,”” a leader in the Sinaloa cartel, told a Mexican journalist he has worried about his sonVicente Zambadasince he was extradited to Chicago in February in the racketeering case there.

Ismael Zambadahas been indicted in that case too. He conceded that he might be arrested “”at any moment, or never.”” He would consider suicide over the rest of his life in a U.S. prison. “”I don’t know if I would have the guts to kill myself,”” he said. “”I want to think that yes, I would.””

U.S. District JudgeLarry A. Burnsin San Diego has handed down stiff sentences. Once these prisoners were millionaires and lived in fortified Mexican villas. Now they come into his courtroom in orange jail jumpsuits and are marched away in handcuffs.

In November 2007,Francisco Javier Arellano Felix, one of the leaders of the Arellano Felix drug trafficking organization, who pleaded guilty to money laundering and running a criminal enterprise, asked for “”forgiveness from all those people on both sides of the border who I have affected by my wrongful decisions and criminal conduct. Please forgive me.””

“”If I had the power to change and undo the things that I have done,”” he said in a letter written in Spanish and translated by his attorney, “”I would.””

Burns was not in the least moved. “”Your name will live in infamy associated with all these terrible things,”” he said. “”It is a record of callousness. It’s a record of cruelty…. All of the mayhem and the murder and the intimidation, all of that has happened, and today is the day of accounting.””

He gave the 37-year-old life in prison, and then tacked on another 20 years.

Jorge Aureliano Felix(unrelated to Arellano), 57, a former Mexican police official who provided security for drug loads to pass through Baja California, had spent four and a half years in a Mexican prison before being extradited to face charges of racketeering and drug smuggling in Burns’ courtroom. On March 29, as he heard Burns describe allegations of “”torture and murder,”” he suddenly had to be escorted out of the courtroom so he could vomit. When he was returned, Burns sentenced him to 30 years in prison, followed by deportation to Mexico if he lived that long.

In Houston in February,Osiel Cardenas Guillen, head of the Gulf cartel that pushes cocaine up through South Texas, was sentenced behind locked doors, with armed guards circling the courtroom of U.S. District JudgeHilda G. Tagle. Guillen had been convicted of drug dealing, money laundering, murder and assault.

“”I apologize to my country, Mexico, to the United States of America, my family, to my wife especially, my children, for all the mistakes I made,”” he told the judge.

She gave Cardenas, 42, who reportedly is cooperating with U.S. law enforcement officials, 25 years in prison and ordered him to forfeit $50 million in assets. He already had served eight years in Mexico since his capture for running cocaine through his home state of Tamaulipas.

“”Innocence lost — that is your legacy to your country, to our communities on both sides of the border and to society,”” she told him.

Next up isEfrain Perez, who appears before Burns on May 3 in San Diego. He pleaded guilty in October to cocaine and marijuana smuggling, and is looking at 30 years and a $250,000 fine. His life in the cartel is over.

“”This is not a business you can retire from,”” said Payan, the El Paso professor. “”Very few grow old in this business.””