"One of the key elements (in the August 25 attack) has been detained," Nuevo Leon state security spokesman Jorge Domene told Milenio television. Roberto Carlos Lopez Castro was detained in the suburbs of the western city of Guadalajara, Domene said. Other suspects behind bars allegedly named Lopez as one of the ringleaders of the cell responsible for the assault on the Casino Royale. Armed men rapidly set the casino ablaze in one of the deadliest attacks in nearly five years of shocking drug violence in Mexico. Forty-two women were among the victims. Ten suspects have now been detained, including a police officer and suspected members of the Zetas drug gang. Authorities blame the Zetas -- a gang set up by ex-elite army officers in the 1990s -- for torching the casino because its owners refused to pay protection money. A surge in violence in Nuevo Leon in recent years is blamed on a turf war between the Gulf drug gang and its former enforcers the Zetas.