This is going to get creepy fast. In the 1880s and 1890s the family of George and Mary brown of Exeter, Massachusetts suffered a sequence of tuberculosis, called consumption at the time, infections. Mary, the mother, was the first to die and then their eldest daughter, Mary Olive, died in 1888. Their son, Edwin, then caught the infectious disease in 1890. Sadly, in 1891, another daughter, Mercy, became infected and died of the disease in January of 1892.
She was buried in the Baptist Church cemetery in Exeter. People began talking about one of the family members being a vampire, as folklore went at the time that if multiple family members died of a disease, then a family member must have been involved in undead activities. George Brown was persuaded to exhume the bodies of his family members in March 1892. While his wife and daughter, Mary Olive, were considerably decomposed, Mercy was still quite preserved and still had some blood in her heart, because they didn’t embalm most people back then.
So, the villagers took that as a sign that Mercy was a vampire and the reason Edwin was sick. Mercy’s heart was removed from her chest, burned, and the ashes mixed with tea and given to Edwin to drink to cure his ailment. He died two months later.