MEXICO CITY (AP) " Volunteer searchers pounded metal probes into hard-packed earth at a clandestine grave site in Mexico's Veracruz state on Thursday, redoubling efforts after receiving a tip that hundreds more bodies may be buried there.
The search by Colectivo Solecito and other groups has so far found 253 sets of remains. They were led to the field on the outskirts of Veracruz city by an anonymous tip: a map drawn by someone familiar with the clandestine burials.
Searcher Manuel Rodriguez says they have now received a similar tip that about 500 bodies altogether were buried there by a drug gang.
While the new tip could not be immediately confirmed by state authorities, the seeming precision of the hand-drawn map " which marked burial sites with small crosses " and similarities between the two tips, gave it some credibility.
Rodriguez said Thursday's search hasn't uncovered any suspected graves, and was meant to rule out an area where the hard-packed soil made it harder to dig burial pits.
"We have information there could be more than 500 bodies," said Rodriguez.
"Right now we are excluding (possible burial sites) in an area where we don't think there are any, but we don't want to leave any possibility out."
Rodriguez, like most of the volunteer searchers, has a missing relative, a cousin who disappeared about three years ago. Most of the burials are believed to be the victims of a drug and kidnap gang.
But experts have identified only two of the 253 bodies exhumed since searches began in August at the site in the hilly fields known as Colinas de Santa Fe. Those bodies were identified largely because the victims were found with ID cards.
That is frustrating both for searchers like Rodriguez and also for investigators, who are running out of room to store the bodies and skeletal remains excavated at this and other sites in Veracruz.
"They aren't working fast enough, with enough urgency," Rodriguez said of the teams trying to use DNA testing to match the remains to people with missing-person reports. "They don't have the right equipment."
Searchers for clandestine graves in Mexico use a technique in which they sink metal rebar rods into the earth and withdraw them, to detect the tell-tale odor of decomposition.
Rodriguez said the graves in Colinas de Santa Fe have been found at depths of as much as 3 meters (10 feet), but have sometimes been as shallow as 70 centimeters (2 feet).
It is still not known who killed and buried the victims, but suspicion has fallen on the Jalisco New Generation cartel.
That gang moved in to Veracruz around 2011, sparking bloody turf battles with the ferocious Zetas cartel.
This story has been automatically published from the Associated Press wire which uses US spellings