The Determination of Authorship from a Homogenous Group of Writers

Forensic document examiners may encounter challenges when examining specimens from homogeneous writing populations and may need to identify potential sources of errors when rendering conclusions of authorship on such writings. A research project was conducted in which samples of writing were obtained from 52 adult writers who grew up in the same neighborhood, were taught the same copybook style, at the same Catholic elementary school, by the same teachers, approximately 4 decades ago. The specimen writings were subsequently examined and compared by 49 forensic document examiners throughout the world. The examiners rendered conclusions of authorship on the writings and submitted their conclusions for evaluation of accuracy. The results of the study offered evidence to support that there is a high degree of inter-writer variation among writers, even in populations where the driving forces for variation were low; and among these homogeneous writing populations, forensic document examiners were able to extract features from the writing samples that enable them to attribute authorship. The study examined effects of certain factors such as examiner experience, geographic location of examiner, and length of the questioned documents and how these factors affected accuracy. The research addressed criticisms that earlier studies on the individuality of handwriting did not include populations from homogeneous writing communities and relied on computer analysis of handwriting rather than on human examiners.