Top Mexican security officials said Thursday that there is no evidence that true paramilitary groups are operating in Mexico, countering video boasts by a shadowy group of masked men who asserted responsibility for the torture-murder of 35 alleged drug cartel members last week.

A group calling itself the Zeta Killers said it dumped the half-naked, bound and beaten corpses of 11 women and 24 men at a busy intersection in the tourist zone of Veracruz last week.

The bodies spilled out of two abandoned trucks just a block from the hotel where Mexico’s state and federal prosecutors were gathering for a meeting. Eleven other bodies were scattered around the coastal city a day later.

In a video released this week to local media and posted on the Internet, the Zeta Killers said that “our only objective is the Zetas,” the criminal organization founded by former Mexican special forces soldiers who now specialize in arms, drugs, sex and human trafficking.

In the video, the Zeta Killers vowed that the vigilantes would not kidnap or extort ordinary residents. The video showed dozens of heavily armed, burly men, their faces covered with black masks, posing for the camera and promising to work for the people.

But who, really, are the Zeta Killers?

Mexico’s security spokeswoman, Alejandra Sota, said Thursday that there is no evidence that paramilitaries operate in Mexico — meaning groups supported by the state or powerful backers or composed of ordinary residents who seek rough justice.

“We stress that they are criminals who belong to a criminal group that wants to seize control of the criminal activities of another criminal group,” Sota said.

Such death squads operated in Colombia during the worst years of the U.S.-backed fight against drug violence there.

In Mexico, vigilante justice is not uncommon, but it is mostly spontaneous eruptions against thieves, rapists and hometown killers.

The Zeta Killers have been tied to the Gulf cartel and Joaquin “El Chapo” Guzman’s Sinaloa cartel.

“They strike me as freebooting killers whose services are up for sale to the highest bidder, who now appears to be the Sinaloa cartel,” said George Grayson, a professor at the College of William and Mary and a specialist in Mexican drug gangs.

This is not the first time that Mexican gangsters claim to be acting on behalf of the people. In the western state of Michoacan, La Familia cartel pledged to protect people there from outsiders — criminals and the government.

Alberto Islas, a security consultant in Mexico City, said that whoever the Zeta Killers are, it appears that its members have had police or military training — given that the dumping of the bodies in rush-hour traffic was so well-coordinated and so precise, their escape was so swift (with no arrests) and the language they used in their video was military-speak.