Guards and officials at a prison in northern Mexico let inmates out, lent them guns and allowed them to use official vehicles to carry out drug-related killings, including the massacre of 17 people last week, prosecutors said Sunday.
After carrying out the killings, the inmates would return to their cells, the attorney general's office said in a revelation that was shocking even for a country wearied by years of drug violence and corruption.
"According to witnesses, the inmates were allowed to leave with authorization of the prison director ... to carry out instructions for revenge attacks using official vehicles and using guards' weapons for executions," office spokesman Ricardo Najera said at a news conference.
The director of the prison in Gomez Palacio in Durango state and three other officials were placed under house arrest pending further investigation. No charges have been filed.
It was not immediately clear how many prisoners or guards were allegedly involved in the shootings.
Prosecutors said the prison-based hit squad is suspected in three mass shootings, including the July 18 attack on a party in the city of Torreon, which is near Gomez Palacio. In that incident, gunmen fired indiscriminately into a crowd of mainly young people in a rented hall, killing 17 people and wounding 18 others.
Police found more than 120 bullet casings, and Najera said tests matched those casings to four assault rifles assigned to guards at the prison.
Tests also linked the guns to earlier killings at two bars in Torreon, the capital of northern Coahuila state, he said. At least 16 people were killed in those attacks on Feb. 1 and May 15, local news outlets reported.
