A Nuevo León state police officer was arrested on suspicion of links to gangsters who started the fire that killed 52 people at a casino in the northern city of Monterrey, a Mexican federal prosecutor said.

José Cuitlahuac Salinas told a press conference that a review of video footage from security cameras at the Casino Royale led investigators to officer Miguel Angel Barraza Escamilla.

Barraza Escamilla was spotted sitting in one of the vehicles in which the arsonists arrived at the casino, the prosecutor said.

The cop's arrest brings to six the number of people in custody for the Aug. 25 atrocity in Monterrey, Nuevo León's capital and Mexico's industrial hub.

Authorities say members of the Los Zetas drug cartel set the casino on fire because the establishment's owners were resisting demands for protection money.

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