Authorities in northern Mexico say they are searching for another seven suspects over an arson attack at a casino that killed 52 people.
Nuevo Leon state Governor Rodrigo Medina said at least 12 people were involved in the attack in the city of Monterrey.
Mr Medina made the comments as officials showed journalists five alleged members of the Zetas drug cartel who have been arrested in the case.
Gunmen on Thursday ignited petrol at the entrance to the Casino Royale.
Terrified customers and employees ran inside the building. Many were found dead from smoke inhalation in offices and bathrooms.
Police are investigating whether the attack was in retaliation for not paying extortion money.