Nine guards have confessed to helping Zetas drug gangsters escape from prison before other Zetas slaughtered 44 rival inmates, a state official said late Monday, underlining the enormous corruption inside Mexico's overcrowded, underfunded prisons. The top officials and as many as 18 guards at the Apodaca prison in northern Mexico had been detained under suspicion that they may have helped 30 Zetas escape during the confusion of a riot early Sunday in which 44 members of the rival Gulf cartel were bludgeoned and knifed to death. Nuevo Leon state public security spokesman Jorge Domene Zambrano said nine of the guards confessed to aiding the escape. He said it appeared the breakout happened before the deadly fight. The massacre in this northern state was one of the worst prison killings in Mexico in at least a quarter-century and exposed another weak institution that President Felipe Calderon is relying on to fight his drug war. Mexico has only six federal prisons, and so sends many of its dangerous cartel suspects and inmates to ill-prepared, overcrowded state penitentiaries. Drug trafficking, weapons possession and money laundering are all considered federal crimes in Mexico. "The Mexican prison system has collapsed," said Raul Benitez, a professor at Mexico's National Autonomous University who studies security issues. "The prisons in some states are controlled by organized crime." AP A child yells out for her father as she... View Full Caption An increase in organized crime, extortion, drug trafficking and kidnapping has swelled Mexico's prison population almost 50 percent since 2000. But the government has built no new federal prisons since Calderon launched an offensive against drug cartels when he took office in late 2006, leaving existing jails overcrowded. Calderon's administration has renovated three existing state prisons to use as federal lockups. Built to hold about 185,000 inmates, the prison system nationwide now holds more than 45,000 above that capacity, according to figures from the National Public Safety System. Of the 47,000 federal inmates in the country, about 29,000 are held in state prisons. That has drawn complaints from Nuevo Leon Gov. Rodrigo Medina and other state governors, who say their jails aren't equipped to hold members of powerful and highly organized drug cartels. The federal government counters that none of the escapes or mass killings have occurred at federal lockups, and it cites corruption on the state level, not overcrowding, as the main cause of the deaths and escapes. "The constant element has been corruption in the control processes" at the prisons, said Patricio Patino, assistant secretary for the penitentiary system. Prison employees say guards are underpaid, making them more likely to take bribes. And even honest guards are vulnerable to coercion: Many live in neighborhoods where street gangs and drug cartels are active, making it easy to target their families with threats. The same can be said for Mexico's municipal police forces, another weak flank in Calderon's attack on organized crime. Thousands of local officers — often, entire forces at a time — have been fired, detained or placed under investigation for aiding drug gangs. "Yesterday, Apodaca, tomorrow, any other (prison)," columnist Carlos Puig wrote in the newspaper Milenio.