At the conclusion of the episode Murdoch describes the personalty traits of his killer as a sociopath without actually using the word. That's understandable as the word was not coined until 1909, a decade later, by Karl Birnbaum in Germany and wasn't popularized in North America until 1930 by educational psychologist George E. Partridge, as an alternative to the concept of psychopathy.
Murdoch seemingly improvises a version of the Dictaphone although the instrument was not invented until 1912.
This episode takes place in 1898.