Seeking patterns in the forensic analysis of handwriting and speech

This chapter examines features of handwriting and speech and their effectiveness at determining whether the identity of a writer or speaker can be identified from his or her handwriting or speech. For handwriting, some of the subjective and qualitative features used by document examiners are investigated in a scientific and quantitative manner based on the analysis of three characters ("d," "y," and "f",) and the grapheme "th." For speech, several frequently used features are compared for their strengths and weaknesses in distinguishing speakers. The results show that some features do have good discriminative power, while others are less effective. Acceptable performance can be obtained in many situations using these features. However, the effect of handwriting forgery/disguise or conscious speech imitation/alteration on these features is not investigated. New and more powerful features are needed in the future if high accuracy person identification can be achieved in the presence of disguise or forgery.