It has now been 100 days since 84-year-old Nancy Guthrie vanished under mysterious circumstances. Her family, including Savannah Guthrie, have grown increasingly frustrated and exhausted, Page Six revealed.There have been no significant breakthroughs or leads in the case despite months of searches, media appeals and law enforcement efforts.Nancy's disappearance has attracted national attention partly because Nancy Guthrie is related to Savannah Guthrie. Savannah has reportedly remained deeply involved in efforts to keep public attention focused on the case.Read more: Nancy Guthrie update: Sheriff opens up about 'secret' info, upcoming arrestFamily says emotional strain is worseningSources close to the family told Page Six that the emotional strain surrounding the case has become increasingly severe as each passing week brings fewer visible developments and diminishing optimism.According to Page Six, the family reported that on Monday, the 100th day mark of Nancy's disappearance, Savannah wore yellow to mark the occasion. Her coworkers wore yellow ribbons as a sign of hope throughout the two months she was gone looking for Nancy. "Nancy is always on Savannah's mind," Page Six reported.Guthrie wasn't on the show on Friday morning. Page Six has revealed that there have been some tears and that she has become frustrated and emotional in between commercial breaks. However, she has been able to quickly gather herself before the cameras resume.“It’s incredibly difficult to grasp that there have been no new viable leads, and no significant evidence beyond the doorbell camera footage. How is that even possible?” a source told Page Six, speaking of Savannah's frustration.Guthrie, her siblings Annie and Camron, as well as everyone else impacted by the case, experience an underlying dissatisfaction and rage that goes beyond the pervasive grief and helplessness.Read more: Nancy Guthrie update: Why are Annie Guthrie, Tommaso Cioni ‘laying low’?Investigation drags onThe Pima County Sheriff's Department in Arizona continues to collaborate closely with the FBI.The Guthrie family has reportedly not engaged any private investigators. The matter is currently being handled at the state level.As for leads, all they have is a single hair for DNA evidence and doorbell camera footage of a masked and armed man. The only other unconfirmed evidence is a glove discovered near Nancy's house.“Although you don’t see his face, you can see his eyes, we know how tall he is, there’s a recognizable backpack....come on," a source told Page Six, describing the doorbell footage.The Guthrie case is still a "major priority," according to FBI sources who spoke to Page Six. Meanwhile, Pima County Sheriff Chris Nanos, who has been under fire for how he handled the investigation, said this week that authorities are coming closer to answers.Nanos said, “Everyday our DNA labs are working with our investigators and they’re coming up with different ideas and different thoughts of how to help them make this DNA work for us.”