Little is known of the backgrounds of the two men whom an early historian called "the most brutal monsters of the human race." One was Micajah, or Big Harpe, and the other was Wiley, also known as Little Harpe. Together they were responsible for one of the earliest recorded rampages of what today would be called serial killings. In the years 1797-1799, they murdered a stunning number of hapless farmers and travelers in Tennessee, Kentucky, and Illinois. Few were spared. Men, women, children, even babies, were numbered among their victims. The Harpes were indeed diabolical in the treatment of their prey. Persons were often mutilated. A knife was driven so deeply into the body of Mary Stegall, one of the victims, that the fires of the burning cabin did not scorch the weapon's handle. The Harpes may well have invented or introduced to the frontier the gruesome practice of disposing of bodies by eviscerating the corpse, filling the cavity with rocks, and sinking the body in a river. No one knows how many persons the Harpes murdered. Historian Otto A. Rothert puts the number at twenty-eight, while Paul Wellman holds that thirty-nine persons died at the hands of the Harpes. (The discrepancy results primarily from the uncertainty as to whether the Harpes were indeed responsible for the murder of three men at the mouth of the Saline River in Illinois and the ambush of the Trisword family and its slaves.)
Mystery surrounds origins of the Harpe brothers. Some persons have questioned whether indeed they were brothers; perhaps they were cousins. Their appearances differed. Micajah, or Big Harpe, was described as tall, with close-cropped black kinky hair and unusually reddish skin. Wiley, or Little Harpe, was at times described as having black hair, but in fact he seems to have been red-headed. Micajah Harpe was said to have spoken with a noticeable Scottish burr. Both Harpes were also rumored to have had some black ancestry. Micajah's appearance lends some credence to this belief. Evidently both brothers were born and reared in North Carolina. There Micajah married Susan Roberts. Her sister, Betsey, came to live with them and became, as some historians have called her, Micajah's "supplementary" wife. Susan, however, was rather plain, while Betsey's beauty was well known. The Harpes migrated with the two women and apparently joined up with several renegade Indians, outcasts from their own tribe. Later the Harpe brothers, along with Susan Harpe and Betsey Roberts, settled near Knoxville, Tennessee. There Wiley Harpe courted and wed Sally Rice, the daughter of John Rice, a respected minister. Nevertheless, the brothers disregarded traditional marital guidelines and shared the three women sexually.
In summary, little definite can be said about the brothers' ethnic background or that of the Roberts sisters. Little is known about the five persons who made up the Harpe band.