Mexico City - A group of drug cartel inmates who were allowed by guards to leave prison to commit murders are believed responsible for the massacre of 17 people earlier this month, the Mexican government said on Sunday.
Mexico's federal prosecutors' office said in a televised statement that the prison staff, including the director, knowingly let out the inmates at the detention centre in Gomez Palacio in Durango state.
"They were allowed to leave the prison and use the weapons of the guards in these executions using official vehicles," said Ricardo Najera, the spokesman for the federal prosecutors' office.
"These criminals carried out their executions as part of the settling of accounts between rival gangs and disgracefully these cowardly criminals then murdered innocent civilians on their way back to their cells."
Drug gang hitmen in five sports utility vehicles stormed a birthday party in the northern city of Torreon on July 18 and gunned down 17 revellers with automatic weapons. Another 18 people were wounded in the attack.
Two prison guards have so far been detained in the investigation into the case, Najera said.
Torreon is one of the northern cities at the heart of the struggle between rival drug gangs to control smuggling routes into the United States.
More than 26 000 people have died in drug violence since President Felipe Calderon launched an army-led crackdown on the cartels after taking office in late 2006.
The worsening violence has alarmed the United States government and risks undermining investor confidence in Mexico, where the industrial sector depends heavily on export sales and foreign investment. - Reuters