Mexican government has admitted that it mistakenly identified Felix Beltran Leon as the son of the country’s most-wanted drugs lord, Joaquin “El Chapo” Guzman.
On Thursday officials paraded before the media a man they said was Jesus Alfredo Guzman, whose father leads the powerful Sinaloa cartel.
But the arrested man was in fact Felix Beltran Leon, a car salesman, the attorney general’s office said.
The authorities had hailed the arrest as the most important in years.
Known as El Chapo” or “Shorty”, Joaquin Guzman has been in hiding ever since he escaped from prison in 2001.
The Sinaloa cartel controls much of the flow of cocaine, marijuana and methamphetamine to the United States.
Within hours of the high-profile arrest, doubts had started to be cast on the official version of events.
A lawyer proclaiming to speak for the Guzman family released a statement denying that the suspect in custody was the drug boss’s son.
Felix Beltran Leon’s mother then spoke to journalists and denied any link to Joaquin Guzman or the Sinaloa cartel.
It took another few hours, while identity tests were carried out, before the government admitted it had made a huge mistake.
In less than a day, the episode has transformed from an apparent coup against one of Mexico’s biggest drug cartels to a major embarrassment for President Felipe Calderon’s administration, our reporter says.
US agencies, such as the Drug Enforcement Administration, were among those that had applauded the arrest.
On Thursday, the Mexican Navy had said that Jesus Guzman – known as “El Gordo”, or “The Fat One” – was a growing force within his father’s cartel and controlled most of its trade between Mexico and the US, where he was indicted in 2009.
El Chapo was jailed in 1993, but escaped from his maximum-security prison in a laundry basket eight years later.
The US state department has offered a reward of up to $5 million for information leading to his arrest.
If nothing else, the debacle goes to underscore how murky and confused the world of drug cartel arrests and government intelligence has become in Mexico.
With few recent photos of the main players in the drug world available, there may be more such cases of mistaken identity to come for the Mexican armed forces.
More than 55,000 people have died in Mexico in drug-related violence since President Felipe Calderon declared war on the cartels nearly six years ago.