A demonstrator holding a Mexican flag is silhouetted during a protest in support of the 43 missing students in Mexico City on Dec. 1, 2014. The head of the country's National Electoral Institute was forced to apologize amid demands for his resignation after audio of him insulting indigenous people went viral online. Reuters

The head of Mexico's National Electoral Institute was forced to apologize after illegally recorded audio of him ridiculing indigenous people leaked online. Lorenzo Córdova Vianello, the director of the group that will oversee the country's elections June 7, was still trending on Twitter Wednesday morning as users passed around the controversial clip.

The audio, thought to have been obtained via wiretap, was posted to YouTube on Tuesday afternoon by "Jon Doe." The roughly two-minute video reportedly includes a part of a conversation between Córdova and his executive secretary, Edmundo Jacobo.

The exchange likely happened after an April 23 meeting where indígenas, or indigenous people, asked to be allowed to create another federal constituency in Congress, Excelsior reported. The indígenas had said they'd stop the elections if their requests weren't granted, and they eventually met with Córdova.

The next day, in conversation with Jacobo, Córdova made fun of what they said. He compared the leaders to characters in the "Lone Ranger" and ridiculed how they spoke, Telesur reported. “From the dramatic meetings with the parents of the Ayotzinapa kids, to this jerk … There was one, no s---, I can’t lie, let me tell you how this jerk spoke,” Córdova said in Spanish. “'I boss, great nation Chichimeca, I come Guanajuato. I say here or legislators, for us, I don’t permit your elections.'”

The governor of the National Indigenous Peoples Government, Hipólito Arriaga Pote, responded to the audio leak with outrage. He said that Córdova's comments showed how the electoral institute treats indigenous people -- the leaders are nice in front of them but nasty behind their backs. "It is very discriminatory to all my indigenous brothers at national level," Arriaga Pote told Excelsior.

At a press conference Tuesday, Córdova took responsibility for the audio, which he emphasized was an act of espionage. Córdova said he offered a "frank apology if I offended anyone with my comments." The National Electoral Institute released a statement of its own condemning Córdova's outburst and announcing it had filed a criminal complaint with the Attorney General's Office over the wiretap, Aristegui Noticias reported.