Nine men's heads were found in plastic bags in the southern Mexican state of Guerrero early Sunday. Eight of them were eventually identified as belonging to soldiers, and the ninth was a lawyer. "grave mistake" for criminals in the illegal drug trade to have decapitated eight soldiers over the weekend, a top Mexican military officer said Monday.Residents of Chilpancingo, the capital of Guerrero, found the heads on a busy city street before dawn, and hours later located the bodies several kilometers (miles) away, local police said."For each member that you kill, we are going to kill ten of yours," read a sign that was found next to the heads. It was signed "You know who," a state security official told AFP.Prosecutors announced late Monday that soldiers had detained seven suspects in the decapitations, all in Guerrero state."The criminals made a grave mistake with this audacious crime," said the local regional commander, Enrique Jorge Alonso, speaking at a ceremony here Monday honoring the slain soldiers.The beheading was "an offense against the (government) institutions and especially to those who wear a military uniform," said Alonso, speaking for Defense Secretary Guillermo Galvan.
The attack was a "sick and despicable act of revenge," Alonso said."There will not be the least concession ... and we will not rest until we have put these criminals where they belong," he added.

The soldiers were apparently kidnapped late Saturday as they left their base in Chilpancingo, located 80 kilometers (50 miles) northeast of the resort town of Acapulco.

The beheadings were the drug cartel's answer to the Friday slaying of three drug cartel members in a clash with soldiers in the town of Teloloapan, also in Guerrero state, the daily La Jornada reported, citing security sources.President Felipe Calderon, speaking in Mexico City, said that the death of the soldiers "had not been in vain."Mexico "will spare no effort to bring to justice those responsible for these cowardly acts," Calderon said.Feuding drug cartels have engaged in a fierce battle to dominate Guerrero state. In the past two years, decapitated victims were recovered there at least three times. Two of those killed were federal police.Separately, 19 people were killed overnight Sunday to Monday in the northern state of Chihuahua in drug related violence, state officials said.
They include 14 people found dead in different parts of Ciudad Juarez, the most violent city in Mexico, located across the Rio Grande from El Paso, Texas.
Those include a couple, both 25, who were killed in a hail of 49 gunshots, said Alejandro Pariente with the Chihuahua state prosecutor's office.Authorities blame most of the violence there to an ongoing war between the Ciudad Juarez drug cartel -- led by Vicente Carrillo Fuentes -- and the rival Sinaloa drug cartel led by Joaquin "El Chapo" Guzman for control of the city, one of the most lucrative points to smuggle drugs into the United States.More than 5,300 people have been killed this year across the country in a wave of drug-related attacks, despite a government clampdown on cartels .