Final answer:
From the biological perspective, a psychologist would look into the man's brain and nervous system to understand the determinants of a serial killer's behavior, focusing on biological and genetic factors.
Step-by-step explanation:
A psychologist who favors the biological perspective would be most likely to look for the determinants of the killer's behavior in the man's brain and nervous system processes. Individuals with a biological perspective focus on physiological factors that may contribute to behavior, such as genetics, brain structures, neurochemical imbalances, and other aspects of our biology that can influence our actions. By examining the brain and nervous system, a psychologist can seek to understand how these biological factors may contribute to the development of a serial killer's behavior. This approach would consider the killer's behavior as a result of biological functions rather than solely environmental influences or past learning.