The brother of the mayor of this northern Mexican industrial city - where an arson attack at a gambling house last week killed dozens - will be investigated for allegedly receiving payoffs from casinos, the governor of Nuevo Leon state said.

Video footage appears to indicate "complicity and corruption," Gov. Rodrigo Medina said of images from surveillance cameras at at least three Monterrey casinos in which Manuel Jonas Larrazabal, brother of Mayor Fernando Larrazabal, is seen receiving stacks of bills.

One of the videos posted on the Reforma newspaper's Web site is dated Aug. 19, just six days before suspected members of the Los Zetas drug cartel set fire to the Casino Royale in Monterrey, Nuevo Leon's capital, and killed 52 people who were unable to escape the flames and smoke.

In remarks to the media, Monterrey's mayor distanced himself from his brother's activities and said if there is evidence that he accepted bribes he should be "brought to justice like any other person."

Fernando Larrazabal, who did not take any questions, said he will ask the Nuevo Leon Attorney General's Office to investigate his brother and added that his sibling will have to clarify any doubts authorities have.

The mayor stressed that his position is "extremely personal" and that "no friend or family member" has anything to do with his leadership of Monterrey.

Larrazabal said that upon taking office he pledged to obey and enforce the law and has since taken decisive action against illegal establishments, including casinos operating outside the law.

For his part, Gov. Medina said an investigation will be conducted "to the end ... no matter who falls," especially considering the "tragic events in which 52 people died."

Authorities must provide clarity and transparency in the wake of the attack on the Casino Royale, according to Medina, who said Mayor Larrazabal should offer an explanation to citizens and indicate if he plans to resign.

A group of criminals set fire to Casino Royale on Aug. 25 in broad daylight. Five suspected Los Zetas members subsequently arrested in the attack told investigators they did not plan to kill anyone and only wanted to intimidate the establishment's owners into paying extortion money.

The suspects told investigators they were scolded by their bosses for killing so many people at the casino, which was the target of an extortion racket common in several parts of Mexico, officials said.

Investigators have obtained videos showing the suspects filling containers at a service station with the gasoline they later used to torch the casino, as well as other images from security cameras that show the suspects' vehicles arriving at Casino Royale, Nuevo Leon Attorney General Adrian Emilio de la Garza said Tuesday.

Since the massacre, authorities have shut down several casinos in various states that were found to be operating outside the law - some protected by controversial court rulings - and lacked basic safety measures.

Owners of some Nuevo Leon casinos have complained that they are extorted by organized crime elements and also by the authorities, who threaten to shutter their establishments if payments are not made.

Several casinos in Monterrey have been attacked by criminals in recent months.

Home to many of Mexico's industrial giants, Monterrey long seemed immune to the drug war that has claimed more than 40,000 lives nationwide since December 2006, when newly inaugurated President Felipe Calderon militarized the struggle with the cartels.

But the metropolis and its suburbs have been battered by a wave of drug-related violence since March 2010.