A Colombian court ordered one of the country's former top drug lords released from prison Thursday, as investigators scrambled to find evidence to support further charges, and possibly his extradition to the United States.

Gilberto Rodriguez Orejuela and his brother Miguel once controlled the Cali drug cartel, an empire that moved multi-ton shipments of cocaine across the globe — including to the United States.

In Thursday's ruling, Judge Luz Amanda Moncada forced the government to release Gilberto Rodriguez as Judge Pedro Suarez had ordered last week. Suarez had also ordered Miguel Rodriguez freed, but Moncada ruled that he must stay in prison to serve out a four-year additional sentence for a bribery charge. That sentence reportedly stemmed from a 1996 attempt by Miguel Rodriguez to buy his way out of prison.

The nation was stunned last week by Suarez's ruling that both Rodriguez brothers should be released after they had served just seven years — about half their sentences for drug trafficking. Justice Minister Fernando Londono immediately accused Suarez of falling prey to the brothers' "gigantic economic power," and began a bribery investigation.

Suarez defended his decision, saying the brothers deserved early release because they had participated in a work-study program in prison.

President Alvaro Uribe halted the release on Saturday as officials strove to keep them behind bars. After Moncada's ruling, however, Londono said the government would respect the judge's decision, even though it was "a terrible blow."

"This is a moment of mourning and pain for the country's image and for the administration of justice in Colombia," Londono told RCN Radio.

Unless U.S. and Colombian investigators file additional charges against Gilberto Rodriguez, he was expected to leave prison within hours.

Dozens of police and soldiers surrounded the Combita prison, outside the town of Tunja, 60 miles northeast of Bogota, to guarantee Gilberto Rodriguez's safety when he left the prison.

The U.S. Drug Enforcement Administration was trying to link the brothers to international crimes committed after 1997, when Colombia's constitution was revised to allow the extradition of its citizens.

The men were captured in 1995, so authorities would have to prove that any new crimes were committed from their cells. In the past, drug lords have been accused of continuing to run their operations from prison.

The United States requested the extradition of the Rodriguez brothers in 1996, but a year later, the Colombian government denied the request.

The Cali cartel took over the world cocaine trade from the Medellin cartel, whose leader Pablo Escobar was killed by police in December 1993. The Cali cartel was accused of bribing top government officials. Former President Ernesto Samper had his U.S. visa stripped after his election campaign was accused of taking millions of dollars from the cartel.

Uribe has been courting the United States for more aid to help fight "narco-terrorism" in Colombia, torn by a 38-year civil war fueled by drug money.

Colombian authorities believe that all the top leaders of the cartel have been jailed or killed, yet remnants of the drug operation still exist in Cali, Colombia's third-largest city, 185 miles southwest of Bogota.

U.S. authorities think William Rodriguez, the son of Miguel Rodriguez, may be one of the new drug leaders in Cali. In August, the United States requested the extradition of the 37-year-old lawyer.