Juan Francisco Sicilia, 24, was found dead in a car along with four close friends on March 28 near Cuernavaca, 90 kilometers (55 miles) south of Mexico City. Police also found the bodies of two close relatives of one of Sicilia's slain friends nearby.
Juan Francisco was the son of Javier Sicilia, a poet and columnist for the daily La Jornada and the weekly Proceso, two of the country's leading publications.
The senior Sicilia was out of the country at the time of the killings, and called for the protests as soon as he returned to Mexico.
"We are sick and tired of you politicians... because in your struggle for power you have torn asunder the fabric of the nation," Sicilia wrote in an open letter released Monday.
"You have been incapable of creating the consensus that the nation needs to find unity," he wrote.
Sicilia derided President Felipe Calderon's massive anti-drug sweep, launched in late 2006, as a "poorly designed, poorly managed, and poorly led" affair that "has left the country in a state of emergency."
While the motive for the crime is unclear, the slaughter has shaken Mexican apathy and compelled activists in 15 cities, including the capital, to organize mass rallies.
In an interview with the daily La Reforma, Sicilia said it was time for the government to negotiate with the country's leading drug cartels.
Mexico has to live with the drug traffickers, he said. If the government "is not conducting the war successfully, then let's go for negotiations. Wars end in agreements, after all... and this is going to end in a pact, sooner or later," Sicilia said.
Why, he asked, does Mexico have to "protect the back" of the United States, a country "that is not helping us at all."
At an earlier memorial service for the victims Sicilia vowed to stop writing poetry. "I can't write poems any more, poetry doesn't exist for me," he said.
Mexico's raging drug war is blamed for most of the 34,600 killings that have been carried out since Calderon launched the nationwide crackdown in late 2006.
Separately an activist group said that 59 women and girls had disappeared in the violent border city of Ciudad Juarez last year.
Across the whole state of Chihuahua, "107 women went missing in 2010 and have still not been found, and 71 of them are minors," the activist group Justice for our Girls said late Monday.
With 59 disappearances including 39 minors in Ciudad Juarez, the city continues to witness "serious human rights abuses against women," the group said, adding the figures were official ones from the Chihuahua authorities.
Most of the minors who went missing were aged between 13 and 17, it added.
The figures are a stark reminder of a wave of killings between 1993 and 2003 when some 400 young women died.
Ciudad Juarez is considered the most violent city in Mexico, with more than 3,100 homicides in 2010.