An ex-FBI agent has highlighted a 'strange' detail in the investigation into missing 84-year-old Nancy Guthrie, whose suspected abduction from her remote Tucson, Arizona, home more than 130 days ago has become a prominent unresolved case in the United States. Fresh scrutiny of the crime scene, and of how the family used cameras on the property, has added new questions to an inquiry already shaped by doorbell footage and the unknown fate of the m…