Final answer:
For a criminalist, the hair cortex is important due to its unique microscopic structures such as pigment, cortical fusi, and degree of medullation, which are useful in forensic hair comparison to potentially link hair samples to individuals.
Step-by-step explanation:
The aspect of the hair cortex that is most important for the criminalist is its unique microscopic structure that includes the specific distribution and appearance of pigment, the presence of cortical fusi, and the degree of medullation. These structural characteristics can be used to compare hair samples under microscopy, and are critical in forensic investigations to establish a connection between the hair and a potential suspect.
Criminalists analyze the hair cortex because it contains the bulk of the hair's pigment and provides detailed information, such as color and pattern, which can link a hair to an individual. Unlike the cuticle and medulla, which can be more uniform, the cortex has particular features that can vary significantly from person to person. It is these unique characteristics that help in differentiating between hairs from different individuals and are therefore highly significant in forensic hair comparison.