Savannah Guthrie posted a new video Sunday night pleading for her mother, Nancy Guthrie's return, and urging whoever is holding her to "do the right thing." The FBI continues to investigate as the suspect's mask and clothing are believed to be from Walmart.

The desperate search for Nancy Guthrie has entered its third week, with investigators hoping for a break in a baffling case that they appear no closer to solving.

DNA that doesn't belong to the 84-year-old or anyone close to her was obtained from her property and is being tested, according to the sheriff.