Mexican prisoners armed, released, to act as hitmen?

[JBeukema]

Initially investigators were puzzled. The killings had all the hallmarks of a drug-cartel hit, but none of those at the party had any connection to the brutal drug war that has deepened in Mexico since president Felipe Calderón dispatched troops to fight cartels in late 2006. The party was advertised as a gay event, but it did not seem like a hate crime.
And then they examined the shells from the weapons. The spent bullets, reports the BBC, matched guns issued to guards at Gomez Palacio prison in neighboring Durango state. State prosecutors now say that a group of prisoners was supplied with guns and official vehicles and released, repeatedly, as contract killers for a drug gang. They are thought to have committed two other mass murders in Torreón this year using the same weapons.

Mexican Prisoners 'Let Out' to Kill as Cartel Assassins - Newsweek