Just weeks before Joaquin "El Chapo" Guzman sneaked out of a maximum security prison in Mexico, the U.S. government had requested formally that the drug kingpin be sent to the United States to stand trial on a variety of drug trafficking and conspiracy charges, the Justice Department said on Friday.

The office of Mexico Attorney General Arely Gomez issued a statement late Thursday saying she told a congressional committee in that country that the extradition request was sent June 25.

Guzman vanished from the prison through a tunnel in the shower floor of his cell on July 11.

Gomez's office said she issued instructions to review the request and submit it to courts for consideration.

A variety of U.S. officials, including lawmakers and law enforcement officials, had called for Guzman's transfer to the U.S. since his arrest in February 2014. Mexican officials, however, said Guzman wouldn't be sent to the U.S. until he had served time for all of his crimes in Mexico.

"That is one of the reasons we pushed for extradition," said Jack Riley, the Drug Enforcement Administration's top agent. "We were afraid of this. Not that (Mexican authorities) weren't capable of keeping him — but he'd escaped before."

Riley, the deputy administrator, hasn't really slept since Guzman's escape. The last week has been a flurry of work speaking with his Mexican counterparts and helping direct U.S. efforts to capture one of the world's most prolific and violent drug lords for the third time since the 1990s.

"This guy caused me one of the best days and worst days of my life in a span of a year," Riley said. "We are doing everything we can to track him down, much like we did a year or so ago when we hooked him."

Before taking over as DEA's operations chief in Washington last year, Riley spent four years in Chicago tracking Guzman and continuing to build a growing criminal case against the drug lord. After Guzman's 2014 arrest, authorities in Chicago, including Riley, called for his extradition to the United States to face trial on a litany of drug trafficking and other charges.

Guzman vanished nearly a week ago through a sophisticated tunnel that opened in the floor of his cell's shower. Two Mexican lawmakers said Thursday that at least 18 minutes passed before anyone was alerted.

A surveillance video of Guzman's cell shows him walking to the shower — where there was a blind spot in the security camera's view — crouching down and then vanishing.

According to internal DEA documents obtained by The Associated Press, U.S. drug agents learned Guzman and his associates were plotting his escape almost immediately after his arrest. The agency did not have information about the weekend escape plan, the documents show.

The warnings were passed on to Mexican authorities, according to a U.S. government official briefed on the case. The official was not authorized to discuss details of the case publicly and spoke only on the condition of anonymity.

Mexican authorities have denied they received any warning about possible escape plots.

As the work begins anew to find Guzman, Riley said he has every confidence that U.S. and Mexican officials will be able to capture him again.

"I really do think we've got him on the run, he's looking over his shoulder," Riley said. "We are going to make it as hard on him as possible."

Mexican authorities have established checkpoints on major highways around the country, distributed 100,000 photos of Guzman to toll booths and put 10,000 agents from various components of the Mexican federal police on high alert since the escape. DEA and FBI officials have met with officials in Mexico City and Riley said he has been in near daily contact with his direct counterparts since Guzman's latest dash from custody.

Guzman's 2014 downfall was more than a decade in the making. First arrested in Guatemala in 1993, he spent nearly a decade in another maximum-security Mexican prison before escaping, reportedly hidden in a laundry basket.

In the 21 years he was on the run, he continued to grow his drug-smuggling empire. But by 2008 DEA agents had found the first crack in the security network he had spent years building and perfecting.

A wiretap recorded the boss himself directly negotiating a heroin deal with Chicago twin brothers who had secretly flipped and become government witnesses.

Six years later, after a series of high-profile arrests of associates, more secret wiretaps and other covert surveillance efforts, the DEA, U.S. Immigration and Customs Enforcement, the U.S. Marshal Service and a highly trained and trusted unit of the Mexican Marines tracked Guzman to a series of safe houses in the Mexican city of Culiacan. Guzman was finally found with his family inside a seaside condominium in the resort town of Mazatlan. Not a shot was fired.

Riley said Guzman's use of cellphones was his undoing in 2014 and likely will be again.

"Clearly that was his Achilles' heel the first time and I think it can be this time," Riley said. "This time when we get him, and I tell you we are going to get him, it may have a little different outcome for him."