Ricardo Palmera is already serving a 60-year prison sentence on an unrelated hostage-taking charge, so the mistrial means little for his future. But the U.S. wanted a conviction to reinforce its stance that Latin America’s largest rebel group is also a drug cartel.The Justice Department has now twice failed to make that case in court. A first trial ended last year with a jury deadlocked at 7-5 favoring acquittal. After days of deliberations following a retrial that could cost more than $1 million, jurors said Monday they could not agree on whether Palmera and his guerrilla allies are drug traffickers.The Bush administration has taken a hard line against the Revolutionary Armed Forces of Colombia, or FARC, spending billions to fight the rebels and the world’s largest cocaine industry. Colombian President Alvaro Uribe, an important drug war ally, has used extradition to the U.S. as a strategy to combat drug cartels.In 2004, Palmera — also known by his nom de guerre Simon Trinidad — became the first FARC member to be extradited.Since then, convicting him has proven harder than expected. His first trial, on charges of supporting terrorism and holding three U.S. contractors hostage, also ended with a hung jury. At a retrial, jurors were again deadlocked on most charges but convicted him of conspiring to keep the three contractors hostage.The FARC, a force of 12,000 fighters, has been battling the Colombian government for four decades in a conflict that claims thousands of lives each year.Palmera has testified at each of his trials. He likens the FARC rebels to the U.S. Founding Fathers and compares the ongoing conflict in Colombia to the American Revolution.Jurors interviewed after the first trial said they believed FARC was in the cocaine business but said prosecutors didn’t prove Palmera himself was a drug trafficker.It’s unclear whether the government wants to bring the drug case to trial for a third time. After the first mistrial, defense attorneys asked the Justice Department to postpone the case until Palmera’s appeals ran out on the hostage case. If he lost, the drug case might not be necessary, they said. But prosecutors strongly objected.