Furthermore, Rivera filled the pages of Sagitario with scathing critiques of the post-revolutionary governments of Mexico, which would again land him in prison. On April 1, 1927, Rivera was arrested for authoring two articles published in Sagitario, denouncing the war of extermination being carried out against the Yaqui tribe in Sonora, and calling President Calles an assassin. For this, Librado Rivera spent seven months in the infamous Andonegui prison in Tampico.

Rivera’s imprisonment didn’t silence him. He continued writing, denouncing the repression against him, and doubling down on his criticism of the post-revolutionary Mexican governments. He turned to other anarchist newspapers, including Cultura Proletaria in New York and La Antorcha in Buenos Aires, to get his word out. In a letter written from prison and published in La Antorcha on October 16, 1927, Rivera wrote:

The Calles-Obregón government that appears discursively to be resisting Yankee capitalism, is in practice a true lackey, who even lends itself to modify and impose the laws that those millionaires crave, as do the politicians and millionaires of Mexico.