The reputed leader of Colombia's biggest drug cartel, his features apparently radically altered by plastic surgery, was identified by Brazilian and American anti-drug agents using advanced voice recognition technology, the man's lawyer said Friday.

Brazilian police had difficulty making a positive identification of Juan Carlos Ramirez Abadia while they investigated an alleged money laundering scheme he orchestrated in hiding in Brazil, but got a break after taping him on the telephone and passing that information to agents with the U.S. Drug Enforcement Agency, said the lawyer, Sergio Alambert.

The recording was compared in the United States to other tapes of Ramirez Abadia's voice, leading to a match that allowed Brazilian police to identify him so he could be arrested, Alambert told the Associated Press.

Richard Mei, spokesman for the U.S. Embassy in Brasilia, declined comment on the voice recognition techniques but said the DEA helped with the Brazilian investigation into Ramirez Abadia.

After the positive ID was made, Ramirez Abadia was arrested Tuesday in a luxurious home on the outskirts of Sao Paulo with a gym, sauna, plasma TVs, a swimming pool and allegedly $1 million in stashed cash. Authorities found another $1 million buried in the garden of another home near Sao Paulo on Thursday, the lawyer said.

Cartel sent 500 tonnes of cocaine to U.S.: indictment

American officials have said they will soon file papers to extradite Ramirez Abadia to face racketeering charges, and Colombian authorities have hinted they may also seek custody of the alleged drug lord.

While Ramirez Abadia initially indicated after his arrest that he would co-operate with drug agents investigating Colombia's drug exports to the United States, he has since changed his mind because he fears his relatives in Colombia would face retaliation, Alambert said.

Ramirez Abadia was indicted in the U.S. in 2004 on racketeering charges as an alleged key member of the Norte del Valle cartel that sent 500 tonnes of cocaine to the U.S. from 1990 to 2003.

Ramirez Abadia is also expected to face Brazilian charges of money laundering, gang formation and use of illegal documents while in the country, but Alambert said his client hopes American and Brazilian authorities will make a deal so he can be sent directly to the United States to serve time in prison.

Police said Ramirez Abadia — nicknamed "Chupeta," or lollipop — arrived from Colombia to oversee his gang's Brazilian investments and underwent plastic surgery at least twice to alter his appearance.

The Norte del Valle cartel emerged as Colombia's most powerful drug gang in the mid-1990s, and the U.S. State Department in September 2004 began offering up to $5 million for information leading to the arrest of its leaders.

Ramirez Abadia was sentenced to 13 years in a Colombian prison in 1996 on drug trafficking and racketeering after turning himself in to benefit from a law that allowed him to avoid extradition by admitting to his crimes. He was released in 2001.

His fortune once reached $1.8 billion, but he is believed to be indebted to other traffickers, the State Department said.