PALM HARBOR, Florida (KTRK) -- Deputies in Florida call it the perfect murder, almost.Two sisters have been charged killing their 85-year-old father four years ago.Deputies responded to a call that 85-year-old Anthony Tomaselli had passed away the previous evening on March 6, 2015.His two daughters, Mary-Beth Tomaselli and Linda Roberts, reported the body. They said he had been ill, suffering from both cancer and dementia.EMS and deputies responded and found no signs of foul play or trauma, and determined that he died of natural causes.Four years later, the sisters' story started to unravel when both became romantically involved with the same man.Police say one of the sisters told him about the incident and how they killed their father. When the man realized what she was saying, he recorded their conversation.On Feb. 13, 2019, the man contacted detectives with the Pinellas County Sheriff's Office and told them he had a recording of Linda confessing to murdering her father in 2015. The man gave the recording to detectives and helped them obtain more recorded statements from both Linda and Mary-Beth regarding the death of their father.On the evening of the murder, the sisters allegedly gave him an excessive amount of sleeping pills and alcohol to try to kill him, but it didn't work. They then attempted to suffocate him with a pillow, but that didn't work either.Police say in the end, the two stuffed a rag down his throat and held his nose and arms until he died.According to the Pinellas County Sheriff's Office, both women were recorded, saying the killing was "premeditated" and that they "euthanized" their father because he was going to die within a couple of months and would not live in an assisted living facility. They also said they "faked" finding their father dead by staging providing him CPR and calling 911 for help.Authorities say there was also an adult in the house who they gave sleeping pills to so she wouldn't know what was going on.Pinellas Sheriff Bob Gualtieri says they probably would have gotten away with it had they not told the man about it in February."In some respects, we sometimes call these things the perfect murder, because there was no sign of struggle, no sign of foul play, he had cancer, he had dementia, he was seriously ill," he said.The sisters have been charged with first degree murder and while being interviewed by detectives, both women admitted to the charges. Linda and Mary-Beth were taken to the Pinellas County Jail.