Final answer:
The modus operandi of the murderer suggested that a skilled surgeon was responsible for the crimes.
Step-by-step explanation:
The modus operandi of the murderer can provide important clues to investigators. In this case, the question presents four options to consider. Based on the information given, option a) is supported because the injuries sustained by the victims were clean cuts to the bone, indicating precision and skill. Option b) can be ruled out because the injuries were not random or disorganized. Option c) can also be ruled out for the same reason. Option d) can be ruled out because there is no evidence to suggest multiple perpetrators.
Therefore, the correct answer is a) A skilled surgeon was responsible for the crimes.