A severed head reportedly accompanied by a note of defiance from organized crime gangs was found outside a military barracks in Veracruz state on Saturday.
The head was found in a box outside the army base in Veracruz city, just hours after the government announced it was sending troops to respond to a shooting attack. The box also held a message saying gangs would continue operating despite the presence of troops, Mexico's Reforma newspaper reported.
The victim's body was found shortly afterward on a street in another neighborhood, wrapped in a sheet.
On Friday, assailants killed four bodyguards assigned to protect the children of a state governor who were vacationing in Veracruz. The killings were latest in a wave of violence across Mexico that has also targeted soldiers and police.
The government began sending additional troops to Veracruz after the slaying of guards protecting the children of Mexico State Gov. Enrique Pena, Interior Secretary Francisco Ramirez said.
Victoria Hernandez, spokeswoman for the Veracruz state prosecutor's office said it appears the gunmen mistook the bodyguards' vehicle for that of a rival gang.
Pena, a widower, also blamed the attack on mistaken identity and said he would not use extra security.
"I rule out that it was against family. It was just confusion," he told reporters in Chalco, outside Mexico City.