Authorities believe they've arrested the leader of Mexico's most-powerful drug gang, but the suspect's family said Monday night that it was a case of mistaken identity.

Ruben Aguilar (search), President Vicente Fox's spokesman, said Mexico's Federal Agency of Investigation (search) captured a man going by the name of Joaquin Romero (search) in a Mexico City shopping mall on Saturday. He said the suspect was being fingerprinted and his DNA checked to confirm his real identity — but that he might be Vicente Carrillo Fuentes (search), believed to be the leader of the Juarez cartel.

"Right now, it is likely Vicente Carrillo Fuentes, but it isn't completely confirmed," Aguilar said.

Mexico's Attorney General's office didn't comment on Aguilar's announcement, however, and the Televisa network raised more doubt by interviewing family members who said Romero was an architect and loving father who had nothing to do with drug trafficking.

Televisa also showed a picture of Romero in which he appeared to look like a photo taken of Carrillo Fuentes. The network suggested that the similarity of the two pictures — and little other evidence — prompted the arrest.

Federal investigators could not be reached to comment on Televisa's assertions.

Drug leaders often use false names and change their appearance to avoid capture. Carrillo Fuentes' brother, Amado, led the cartel until 1997, when he was believed to have died during botched plastic surgery.

If the arrest is confirmed, it would be a blow to the Juarez cartel, the only drug gang that hasn't had a top leader arrested amid a nationwide crackdown.

As rival organizations — including the Gulf cartel and the feared Arellano Felix gang — lost their leaders to government operatives, the Juarez cartel flourished and has been waging a bloody battle for control of drug routes all along the U.S. border.

But U.S. and Mexican law enforcement authorities say Carrillo Fuentes' influence within the Juarez organization has been on the decline.

Juan Jose Esparragoza (search) — also known as "El Azul," or Blue — has worked his way to the top of the organization along with several other men with close ties to cocaine producers in Colombia, according to the Mexican Attorney General's office and the FBI.

The Juarez-based gang's power became legendary in the 1980s and 90s under Amado Carrillo — better known as "The Lord of the Skies" — for flying planeloads of cocaine into the United States.

In recent months, the Juarez cartel's battle to control the few spots out of its reach along the U.S.-Mexico border — mainly the city of Tijuana to the west and the stretch of border between Nuevo Laredo and Matamoros to the east — has left scores dead and prompted U.S. officials to warn tourists about traveling to Mexico's northern border area.