Seven police officers in Mexico are under investigation after they allegedly did nothing to stop the killing of their boss, authorities said.

Nuevo León state security spokesman Jorge Domene Zambrano says the officers stood by while Police Chief Germán Pérez in Santa Catarina was attacked.

Domene says those under investigation include Pérez's bodyguards and officers who were guarding the police station.

The spokesman says Santa Catarina's public safety secretary is also being questioned, but he doesn't say whether that official suspected in the attack.

Nuevo León Gov. Rodrigo Medina says several Santa Catarina officers were fired over the weekend and investigators are studying whether revenge was the motive for the attack.

Based on reporting by The Associated Press.

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