Francisco Guerrero Perez killed women in the northern edge of Mexico City through the 1880s and left their bodies at the Consulado river. Around twenty deaths are attributed to him between 1880 and 1888, and one more in 1908. He is usually called the first documented serial killer in Mexico, which is a statement about what the records hold rather than about who was first.
The victims were women working as prostitutes in and around Peralvillo, a poor district on the city's northern boundary. He approached them as a client, took them somewhere private, and strangled or cut their throats. The bodies were left near the river. He was known in the district by sight and by nickname long before he was arrested: El Chalequero, from the vest he wore and kept wearing after the name was attached to him. That is the difference between this case and the London murders it is always compared to. He was not hidden. Nobody with the power to act was looking.
He was arrested on June 13, 1888 and sentenced to death. Porfirio Diaz commuted the sentence to twenty years, which he served at the fortress of San Juan de Ulua. He was released in 1904, sixteen years in; accounts of the release say his papers were filed with a batch granted clemency, and no better explanation of it has been published.
In 1908 the body of a woman in her forties was found in the same part of the city. He was arrested again, convicted again, and died at Lecumberri prison in Mexico City in November 1910, aged about seventy. How many killings the 1888 court actually found against him is not recoverable from anything this archive can reach: the figure of about twenty is what has been attributed to him since, and it should be read that way.