Mexican federal law enforcement officials said seven people who were being questioned in the jailbreak of drug lord Joaquin "El Chapo'' Guzman have been formally arrested and taken to a prison to await charges.
Officials have been questioning more than 30 prison guards and officials since the escape.
Mexican police are also engaged in a larger manhunt in the country, stepping up border security and shutting down an international airport, in addition to checkpoints.
But there is still no sign of Guzman, widely considered to be the world's richest and most powerful drug lord before his capture last year.
He slipped away from the Altiplano prison, about 90 kilometers west of Mexico City, on July 11 after 17 months behind bars.
Authorities say he climbed down a 10-meter ladder in a shaft under his prison cell's shower area and disappeared into a sophisticated 1.5-kilometer tunnel with ventilation, lighting and a motorcycle apparently used to move dirt in the tunnel's construction.
Guzman escaped into a gray brick building on a hill surrounded by pasture land. Investigators released a video showing the hole inside the building's dirt-covered floor. A bed and a kitchen were in the building, indicating that people may have lived there.
Guzman's escape is a major embarrassment for Mexican President Enrique Pena Nieto.
His crowning achievement in Mexico's war on drug cartels and their elusive kingpins was the capture of Guzman, who had been on the run for 13 years after an earlier escape.
The United States, where Guzman faces drug cartel charges, has pledged any support Mexico needs in recapturing Guzman.
American authorities had sought to extradite Guzman to stand trial in the U.S. but were rebuffed by Mexico.
Escape plans known
The Associated Press reported that U.S. Drug Enforcement Administration officials knew of several Guzman escape plans almost immediately after his capture last year, although not of the latest escape.
The drug agency documents claim that Guzman was directing some of his Sinaloa drug cartel operations from prison.
"Despite being imprisoned in a `high security' facility, DEA reporting further indicates Guzman was able to provide direction to his son and other cartel members via the attorneys who visited (him) in prison and possibly through the use of a cellphone provided ... by corrupt prison guards,'' one document said.
The Sinaloa cartel is known for the elaborate tunnels built underneath the Mexico-U.S. border to transport cocaine, methamphetamines and marijuana, with ventilation, lighting and even railcars to easily move products.
The Sinaloa cartel controls most of the border crossings for illegal drugs between Mexico and the United States.