A prominent Mexican news photographer was among five people found dead in a middle-class neighborhood of the capital on Friday, the city's prosecutor told reporters at a Sunday press conference.
Ruben Espinosa, who a month ago claimed in interviews that he felt threatened by the governor of eastern Veracruz state, was the lone male among five victims that police discovered bound, beaten and shot in the head in the capital's Narvarte neighborhood.
The murders prompted hundreds of photographers, other journalists and activists to gather at the capital's Angel of Independence monument, many holding signs or cut-out photos of Espinosa with cameras slung over their shoulders.
One sign said "Violence is the language of the state," another called for Veracruz Gov. Javier Duarte to resign.
Protestors in Xalapa, the capital of Veracruz, and Guadalajara, Mexico's second biggest city, also took to the streets to mourn Espinosa's death.
Mexico City prosecutor Rodolfo Rios said at a press conference that Espinosa's family members told investigators that the photographer had been residing in the capital for two months and had moved to the city to look for work following eight years living in Veracruz.
Rios said his office was working together with the division of the federal attorney general's office dedicated to crimes against freedom of expression.
"All lines of investigation are open," he said in response to a question about Espinosa's early June statements that he felt threatened by Duarte, a member of the Institutional Revolutionary Party (PRI) of President Enrique Pena Nieto.
The governor said in a brief press release on Sunday that he "lamented" the deaths, including Espinosa's, and voiced his support for the investigation led by the Mexico City prosecutor's office.
The prosecutor said robbery and the deliberate targeting of the women were also possible motives being considered.
Espinosa, who was 31 years old, had specialized in documenting local social movements in Veracruz, many of which are critical of the PRI and Duarte in particular.
He shot a cover photograph of Duarte for an issue of leading Mexican news magazine Proceso in February of 2014 that was accompanied by the headline, "Veracruz, lawless state."
Espinosa worked for Proceso as well as the Cuartoscuro photo agency.
Veracruz is one of Mexico's most dangerous states for journalists, with 17 killed since 2000 according to journalism advocacy group Article 19. According to the Committee to Protect Journalists, 11 have been murdered since 2010 during Duarte's term as governor.