Article continues below advertisementDr. Gary Brucato, a forensic researcher and clinical psychologist, told NewsNation that the person responsible for Nancy Guthrie's disappearance is likely someone she knew or with whom she had a "passing relationship."Appearing on NewsNation with senior national correspondent Brian Entin on Wednesday, April 15, Dr. Brucato said that it's likely the 84-year-old mother of Today show co-host Savannah Guthrie is dead and will not be found intact.He also noted that roughly 92 percent of women who are killed in the U.S. know their killer.