NBC "TODAY" co-host Savannah Guthrie made a desperate plea for the public's help in a social media post Saturday morning, exactly six months since her mother Nancy was reported missing. We have lived every moment, every breath, and every heartbeat in agony and despair ever since," Guthrie wrote to open her Instagram message. NANCY GUTHRIE RANSOM NOTES DON'T MATCH SUSPECT'S BEHAVIOR, PROFILER SAYS: 'I DON'T BELIEVE THEY'RE REAL'The 84-year-old Nancy Guthrie was last seen outside her home in the Catalina Hills near Tucson, Arizona, Jan. 31. The newly released ransom notes, which the sheriff's department said were sent Feb. 2 and Feb. 6, demanded a ransom of $4 million to be paid in Bitcoin, while the author threatened to kill Nancy Guthrie. NANCY GUTHRIE RANSOM NOTE CLAIMED THAT SHE HAD DIED, BEEN ‘BURIED WITH NATURE,’ SOURCE SAYSThe second note claimed that Nancy Guthrie had "perished."