CALGARY — As the search for Today Show host Savannah Guthrie’s mother enters its fourth day, authorities say they remain optimistic she is still alive, even as investigators uncover increasingly troubling evidence.Nancy Guthrie was last seen at her Tucson, Arizona, home on Saturday night.Since then, the case has escalated amid alleged ransom demands and signs of a violent abduction.The Pima County Sheriff’s Department believes the 84-year-old Guthrie was kidnapped sometime between when she was last seen by her daughter, Annie, on January 31, around 9 p.m., and when a friend from church called the family the next day to report she had not attended services.Investigators have designated the home a crime scene after discovering suspicious circumstances, including signs of forced entry, according to a person familiar with the investigation who spoke with the Associated Press.Several of Guthrie’s personal items — including her cellphone, wallet, and car — were still inside the home..NewsNation reported Tuesday that a blood trail was discovered leading from the front door of the residence after authorities cleared the scene and released the property to the family.Detectives collected DNA samples confirmed to belong to Guthrie, though did not say whether the samples were blood.A Ring camera mounted at the front of the home appeared to have been removed, and investigators are examining that development.The house is equipped with multiple security cameras, and detectives are working to determine how many were present and whether any footage is recoverable.Authorities are also attempting to access data from Guthrie’s pacemaker, which reportedly stopped syncing with her Apple devices around 2 a.m. Sunday.More than 100 investigators are now assigned to the case, and officials are awaiting results from DNA testing and fingerprint analysis.“That lab will report back to us what they find,” Pima County Sheriff Chris Nanos said.“So far, what we’ve found from that lab is nothing that would tell us this is who did this.”.The Pima County Sheriff’s Department has confirmed it is investigating potential ransom notes reportedly sent to TMZ and a local Tucson news outlet, demanding millions of dollars in Bitcoin for Guthrie’s release.Officials said investigators have not identified a suspect or person of interest.Guthrie is described as 5-ft., 5-ins.,150 pounds, with brown hair and blue eyes. It is unknown what she was wearing when she disappeared.Savannah Guthrie has reportedly been staying with her two older siblings at a nearby family home and is receiving regular updates from investigators.NBC Sports announced she would not travel to the Olympics, saying she is stepping away from work to be with her family as the search continues.