COSAMALOAPAN, México : The bodies of 31 people, some mutilated, have been exhumed from a mass grave in Veracruz, a stronghold of the Zetas, one of Mexico’s most bloodthirsty cartels, a military official said. The bodies were of 24 men and seven women, the official said, raising a toll of 28 given earlier by prosecutors. The bodies were found Monday at an abandoned ranch by members of an army patrol. The motive of the killings is not known. Some of the victims had been in the grave for more than a month, said Arturo Herrera, a prosecutor in Veracruz. Eleven of the bodies had been decapitated, several were missing hands or feet and investigators also found ears and fingers, said a state police official who oversaw the exhumations. Herrera said they have been exhumed over the course of the past two days. There have been numerous mass graves found all across Mexico since the government in 2006 launched a military offensive against drug cartels. After President Enrique Pena Nieto took office in December 2012, the government said it had a database of 26,000 missing people, although it has since said that that figure might be revised downward.