Authorities in Mexico's Tamaulipas state are investigating seven officials at the prison in Nuevo Laredo, just across the border from Laredo, Texas, where 59 inmates escaped and seven others died last week, a high-level state official said.
Warden Alfonso Ramirez Garza and six guards are being investigated in connection with the mass escape from the Cedes 2 prison, Tamaulipas Public Safety Secretary Rafael Lomeli said.
Besides the 59 escapees, five guards remain unaccounted for in the wake of last Friday's escape.
Tamaulipas is one of the main battlegrounds in a turf war between the Gulf cartel and Los Zetas, a band of Mexican special forces deserters turned hired guns.
More than 400 inmates escaped from prisons in Tamaulipas between January 2010 and March of this year due to corruption among prison officials, the federal government said.
The Cedes 2 penitentiary was the scene of another mass escape last December, when 151 inmates managed to get away.
Friday's mass escape came less than two months after 17 inmates tunneled their way out of a prison in Reynosa, a city across the border from McAllen, Texas.
In March, the person appointed to run Cedes 2 after the disappearance of the warden who presided over the December escape was stabbed to death by an inmate.
Forty-one guards were charged in connection with last year's breakout from Cedes 2.
Tamaulipas has also been the scene of several mass kidnappings of migrants headed from Mexico to the United States, as well as of Mexicans traveling in the border region who were later murdered by criminals.
More than 1,000 army troops have been deployed in Tamaulipas in recent weeks to support state and local law enforcement agencies in their struggle with organized crime.
Over the weekend, the Federation of Chambers of Commerce, or Fedecaco, said the federal government was to blame for the mass prison escapes in Mexico because it allows severe overcrowding at penitentiaries.
Fedecaco warned more than two years ago of the risk of mass escapes from prisons "if the federal government did not deal with the problem of overcrowding," Fedecaco vice president Julio Almanza Armas said in a statement.
The prisons in Tamaulipas are holding more than 2,000 dangerous inmates arrested on federal charges who belong to drug cartels and other organized crime groups, "making it essential for the federal government to respond to the S.O.S. from the state and not be deaf to it," Almanza said.
Mexico's drug cartels sometimes engineer mass prison breaks in response to the killings and arrests of their gunmen.