Key keywords: Nancy Guthrie, US-Mexico border remains search, anonymous tip cold case lead, missing person cross-border investigation, buried human remains northern Mexico, cold case closure for families, FBI Mexico joint law enforcement operation Law enforcement officials from both the United States and Mexico have launched a formal search operation for Nancy Guthrie, a 43-year-old Arizona woman who was reported missing in 2017, after an anonymous tip submitted to the FBI earlier this month claimed her remains are buried in a remote desert area of northern Mexico less than three miles south of the Arizona border. Guthrie was last seen leaving her home in Tucson, Arizona, on June 12, 2017, telling family members she was traveling to a cross-border community to meet a contact for a work-related errand. She never returned, and her abandoned car was found three days later parked near a port of entry on the US side of the border, with her wallet and phone still inside. For six years, the case sat dormant as a cold case, with investigators unable to locate any witnesses or physical evidence linking her disappearance to foul play, despite multiple public appeals for information. The anonymous tip, submitted through the FBI’s confidential tip line on October 3, included specific GPS coordinates for the burial site, as well as unpublicized details about Guthrie’s disappearance that have only been shared with law enforcement and immediate family members, leading investigators to deem the tip highly credible. A joint task force made up of FBI agents, Mexican federal law enforcement officers, search and rescue teams, and specially trained cadaver dogs arrived at the site on October 18 to begin the search operation. Officials leading the search note that the rugged, cactus-dotted desert terrain in the area will slow search efforts, as teams have to clear thick vegetation and navigate uneven ground to avoid damaging any potential evidence. As of October 22, no human remains have been recovered, but task force leaders say they plan to continue searching the 12-acre designated area for at least two more weeks, with drone surveillance being used to map the site and identify areas of interest for ground teams to explore. Guthrie’s older sister, Lisa Marlow, released a statement to local media on October 21 saying, "We have spent six years wondering what happened to Nancy, and this is the first real lead we have ever had. We are grateful to the anonymous person who came forward with information, and we are holding out hope that we can finally bring her home to lay her to rest with the dignity she deserves." Investigators are still asking anyone with information related to Guthrie’s 2017 disappearance to contact the FBI’s Tucson field office, noting that even small, seemingly insignificant details could help move the case forward. They have not released any information about potential suspects, citing the active ongoing investigation.