Nancy Guthrie Search Picks Up In Mexico After Anonymous Tip About 'Grave'

Nancy Guthrie's search efforts reignited after a group that looks for missing people received an anonymous tip claiming her remains were buried in an unmarked grave in Mexico.

Buscando Corazones Nogales -- a Mexican volunteer group that searches for missing people -- says they got the chilling tip Wednesday ... and they scrambled folks to a remote area near the U.S-Mexico border to try and locate her.

Nancy was abducted in February from her home in Tucson, Arizona ... about 70 miles from the border.

The search group says they found 25 unmarked graves ... but there was no trace of Nancy.

Pima County Sheriff's Department released a statement saying Mexican authorities did not contact them regarding the tip or the search.

PCSD says their investigation remains ongoing, and they would follow up on any credible information.

Even with no sign of Nancy, the group -- which conducted the search with the help of the Sonora State Commission for the Search of Missing Person -- says it's not giving up and plans to return for more searches in the area.