But in May 2008, Giraldo and 14 other paramilitary warlords were extradited to the United States on drug-trafficking charges and, according to Colombian prosecutors, stopped cooperating with Colombian investigators. Victims' families say they still do not know about the financiers and power brokers behind a paramilitary army that wreaked havoc until a recent disarmament.

Colombia's Supreme Court recently halted the extraditions, saying that transferring some of this country's most notorious warlords to the United States violated victims' rights by paralyzing an ambitious truth-seeking process designed to close a violent chapter in the conflict.

The decision will not affect the extradition of drug traffickers with no paramilitary links, the majority of the more than 900 people shipped to face American justice during President Álvaro Uribe's seven years in office. But the court's decision undercuts a priority of U.S. justice: the prosecution of paramilitary commanders who built extensive cocaine-trafficking networks. These cartels, some still in operation, helped arm and supply anti-guerrilla militias that once boasted 12,000 fighters.

"It's almost unprecedented to try and get two separate, independent, sovereign legal systems to actually cooperate at all the necessary levels," the U.S. ambassador here, William R. Brownfield, said in an interview.

Nearly three years ago, commanders enticed by offers of leniency began outlining their crimes -- many committed with help from military units and corrupt lawmakers -- in specially tailored hearings in Colombia. More than 1,200 public depositions of commanders have since been held.

Investigators have determined that paramilitary militias are responsible for 24,000 killings, wide-scale disappearances and the theft of billions of dollars in land.

Victims' rights groups and some government investigators here say the results of the process have been mixed. No commander has been convicted of war crimes, and an effort to return stolen land to victims' families has been hamstrung by bureaucratic red tape.

For some victims, perhaps most troubling is that commanders with the broadest historical knowledge of the paramilitary movement, including details of its links to Colombia's power structure, are now in U.S. jails. The attorney general's office here said that only three of the commanders have continued giving testimony in depositions run by Colombian prosecutors and seen by victims in Colombia via closed-circuit television.

"They have the most vital information, the most important and substantial information that leads to the men behind the movement," said Iván Cepeda, the leader of a victims' rights group whose father, Sen. Manuel Cepeda, was killed by military and paramilitary operatives in 1994.

Because of the testimony offered by Giraldo, once a feared commander on the Caribbean coast, Bela Henríquez knows he was the one who ordered her father killed for organizing poor farmers along a vital cocaine-trafficking corridor. But she knows little else about the 2001 slaying of her father, Julio Henríquez.

Giraldo "limited himself to saying, 'Yes, yes, he's a person I killed,' " said Henríquez, 25. "That doesn't mean that there's been justice; that doesn't mean that he's paying for his crimes."

High-ranking officials in the Uribe administration say, however, that the extraditions of the commanders have helped investigators in reconstructing paramilitary crimes.

"When they were here, there was no justice and peace," said Eduardo Pizarro, director of the National Reparation and Reconciliation Commission. "They didn't clear up anything; they didn't admit anything."

But in its Aug. 19 ruling, Colombia's Supreme Court said the extradited commanders -- eight more have been shipped north since May 2008 -- have stopped confessing their crimes. The court's investigative magistrates concluded that the extraditions jeopardized Colombia's international obligations to resolve "crimes against humanity."

In an interview, Supreme Court President Augusto Ibañez said the court sees extradition as a helpful tool in the fight against drug-trafficking mafias. But he said the United States and Colombia need to ensure that extradited paramilitary chieftains comply first with Colombian war crimes investigations.

"The court will cooperate fully if the circumstances change, if there are solutions in the Colombian proceedings and if victims' rights are guaranteed," Ibañez said.

Court officials also complain that little is known in Colombia about agreements the warlords are making with American justice authorities, though the Uribe administration had pledged transparency in the war crimes investigations. Pre-sentencing plea deals involving at least two of the commanders are sealed.

American officials characterize the problems as mostly logistical and diplomatic in nature. To set up the necessary video-teleconferences with paramilitary commanders jailed in the United States, Colombian authorities need visas and permission from judges, prosecutors and prison wardens, a process that U.S. officials say can take up to two months.

Among those frustrated by the process is the commander considered the most cooperative, Salvatore Mancuso, a former rancher whose militias are said to be responsible for 10,000 crimes.

Now at the Northern Neck Regional Jail in Warsaw, Va., Mancuso complains that he does not have a phone to communicate with Colombian investigators or a computer to track details of his crimes.

Mancuso has participated in three depositions with Colombian investigators since arriving in the United States, Colombia's attorney general's office said. But Mancuso contends that he was extradited to keep him from revealing links between his organization and Colombian military, business and political leaders.

"Once I started to tell truths, the government became uncomfortable," he said from jail, "and the way to stop that was to exile me."