After working with US intelligence for months, the Mexican navy said it believed it had nabbed a big prize in a known Guadalajara narco-haven: the son of Mexico's top fugitive drug lord.
But it turned out they got the wrong man.
The man arrested on Thursday as the presumed son of Joaquin "El Chapo" Guzman is really Felix Beltran Leon, 23, and not Alfredo Guzman Salazar, as the Mexican navy had presented him, the attorney general's office said on Friday.
The stocky, baby-faced suspect had been presented as the son of Guzman, the chief of the Sinaloa Cartel, and a navy official described him as a rising operator in the international drug trafficking organisation.
But Beltran Leon's wife, Karla Pacheco, said he is the father of a toddler and works with his mother-in-law at a used car dealership.
The attorney general's office said that "necessary tests" had proved he was not the drug lord's son, but said he would remain under investigation for the guns and money found during his arrest.
"There is total confusion, which is having a serious effect on their personal and family situation," said Beltran Leon's lawyer, Veronica Guerrero.
Elodia Beltran, who appeared with Guerrero at a press conference on Friday, said she is the mother of the detained man.
"He's never been arrested," she said. "This is a real injustice."
Al Jazeera's Franc Contreras, reporting from Mexico City, said, "This really is a blunder and couldn't come at a worse time, with Mexico just one week away from choosing a new president".
Our correspondent said the mishap would hurt the public perception of both the current president and the candidate from his ruling party in next Sunday's election.
The attorney general's office issued a statement earlier on Friday saying that the original information on the man's identity came from the US.
"We've never had any links to drug traffickers ... He's not the person they say he is."
- Karla Pacheco, wife of the detained
The US Drug Enforcement Administration (DEA) said the information came from Mexico.
"The Mexican navy and Mexican law enforcement have said this is El Chapo's son and that's what we took," said DEA spokesman Rusty Payne, noting that the DEA was working separately to confirm the man's identity.
Pacheco showed AP news agency what she said were her husband's voting credential and driver's license.
She said the couple and their one-year-old were sleeping in their home in Zapopan, a suburb of the western city of Guadalajara, when marines kicked in the door and arrested her husband and his half-brother, 19-year-old Kevin Daniel Beltran Rios.
Authorities also identified Beltran Rios as an alleged member of the Sinaloa Cartel.
Beltran Leon bears only slight resemblance to a photograph of Guzman's son recently issued by the US treasury department.
Guzman Salazar and his father were both indicted on multiple drug trafficking charges in the US District Court for the Northern District of Illinois in August 2009, the treasury department said earlier this month, when it announced it had placed financial sanctions on Guzman and his mother, Maria Alejandrina Salazar Hernandez.
Questions over weapons
Beltran Leon and Beltran Rios were found with a grenade launcher and four grenades, two assault rifles, two pistols and $135,000 in cash when they were arrested, the Mexican navy said.
Pacheco said there were no drugs or guns, but the family did have the cash because of a recent home sale.
Another lawyer, Heriberto Rangel Mendez, said the government planted the weapons.
Zapopan has been the scene of much drug violence and arrests. It is where Guzman's other son, Ivan Archivaldo Guzman Salazar, also known as "El Chapito," was detained on money laundering charges in 2005, and where top Sinaloa lieutenant, Ignacio "Nacho" Coronel, was killed in a 2010 shootout with Mexican army.
Pacheco said her husband works at Autos Pacheco, a used car dealership that gunmen attacked in May, killing one man. The target was a customer looking at cars, not the business, Pacheco said, though media reports said the dealership owner was killed.
"We've never had any links to drug traffickers," Pacheco said. "He's not the person they say he is."
The possible misidentification could be embarrassing for both the US and Mexico in the cat-and-mouse game they are playing with Guzman, who has been on the run since escaping from a Mexican prison in a laundry cart in 2001.
Both countries are conducting an intense manhunt for Guzman. The treasury department has called him the world's most powerful drug lord.
Mexican authorities said they narrowly missed him in February as he was vacationing in the Baja resort of Los Cabos under the nose of heavy security during an international meeting of foreign ministers, including US Secretary of State Hillary Clinton.