The investigation into a deadly arson attack on a Mexico casino has taken a new turn after surveillance photos and videos surfaced showing the local mayor's brother accepting wads of cash at a casino just days before the attack.

Mexican newspapers and websites published the images Wednesday. They show Manuel Jonas Larrazabal, the brother of Monterrey Mayor Fernando Larrazabal, at several casinos in recent months taking payments, though it is unclear what the payments were for or if they were illegal.

Mayor Larrazabal responded Wednesday by saying he was not responsible for his brother's actions and that if a crime was committed, he expected his brother to be held accountable to the law.

Last Thursday, armed men carrying gasoline burst into the Casino Royale in Monterrey and set it on fire, killing 52 people. Police are investigating whether the attack was linked to extortion. Authorities say five alleged members of the Zetas drug cartel have confessed to involvement in the attack. Seven other suspects are being sought.

The images of Mayor Larrazabal's brother have sparked speculation government corruption may also have played a role in the attack.

Mexican President Felipe Calderon called the attack “barbaric,” saying it was the worst on innocent civilians in Mexico in a long time. Mexico offered a $2.4 million reward for information leading to the arrest of the suspects.

Rodrigo Medina, the governor of Nuevo Leon state where the casino is located, is pushing for stricter enforcement and stronger regulations limiting betting operations in his state.

Organized and drug-related crime in Mexico has killed about 41,000 people since late 2006, when President Calderon took office and began a military campaign against his country's drug cartels.