MORELIA, Mexico (Reuters) - Police in the western Mexican city of Morelia have found the bodies of 21 men next to notes identifying them as criminals and warning of more killings to come, authorities said Thursday.
The victims, thought to be aged between 20 and 35, were laid out in groups near the five main highway exits to Morelia, the capital of Michoacan state and where President Felipe Calderon was born and served as governor.
A spokesman for the Michoacan state prosecutors' office said it was too early to say who was behind the killings, which could end up on the tally of more than 38,000 deaths attributed to the war on drug cartels that Calderon declared after taking office in 2006.
Warning notes were left next to the bodies, some of which showed signs of torture, authorities said.
"Because society demands it, here are the thieves, muggers and rapists, and there are still more to come," one read.
Michoacan has been plagued by sporadic violence and is home to one of Mexico's most notorious cartels, La Familia. Last month police said they had struck a serious blow to the gang, killing 11 suspected members and arresting 36 others.
The spokesman for the prosecutors said three of the victims had been shot and the others appeared to have been asphyxiated.
The violence has sparked national protests in Mexico, hurting Calderon's conservative National Action Party (PAN) and stirring fears that tourism and investment could suffer in the world's seventh biggest oil exporter.
Calderon's approval rating has recently slipped below 50 percent for the first time, pollster Mitofsky said.
Michoacan holds a state election in November, and the president's elder sister Luisa Maria Calderon is among the PAN front-runners expected to seek the office of governor.
Daily newspaper Milenio said that Wednesday was the third most violent day on record since Calderon took office.
(Reporting by Leovigildo Gonzalez in Morelia and Dave Graham in Mexico City; Editing by Xavier Briand)