The objectives of the present study were to identify sex from thumbprints ridge thickness using likelihood ratio and posterior probability density as well as to determine which of the three areas of thumb has more potential in sex determination. This was a cross sectional study which involved 194 subjects (97 males and 97 females) within the age range 18-25 years. Ridge thickness was examined within the 25 mm2 areas (ulnar, radial and proximal) which made up of 1164 areas of the thumbprints. Females exhibited finer ridge count compared to males in ulnar area of both sides of the thumbs. In the radial area females were found to have finer ridge counts as in ulnar side, but with some coarse ridge. For the right proximal ridge thickness, a similar trend to that in the radial area was noticed, however, in the left thumbprint, males tend to have finer ridge counts compared to females. It was noticed that chance of sex inference from likelihood ratio decreased in the following order: proximal ridge thickness < radial ridge thickness < ulnar ridge thickness as ridge thickness decreases in favor of females but left proximal ridge thickness showed increased in likelihood ratio as ridge thickness decreased in favor of males. In conclusion, considering equal probability for each sex, likelihood ratio reveals the applicability of ridge thickness in sex inference among Hausa population. Ridge thickness in ulnar area showed more discrimination power compared to other two areas.
Key words: Forensic sciences, likelihood ratio, Hausa population, ridge thickness, sex inference.
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