|Photo Credit Ell Brown|
Indeed, another mystery writer used this technique. Agatha Christie's third, Hercule Poirot novel, The Murder of Rodger Ackroyd, tells the story from the Point of View of a Dr. Shepherd who calls on a retired Hercule Poirot to investigate the crime. :::Spoiler Alert::: Turns out that Dr. Shepherd is in fact the murderer and the faces of the case are found in his journal.
Christie also has Poirot's friend Captain Hastings write a number of the books.
This POV can be useful in both cases because the main characters are brilliant, but a bit hard for the average person to understand. Holmes, for instance, could name scores of different types of tobacco ash, but didn't know the earth circled around the sun because that didn't help him with solving crimes. Poirot (much like his 21st Century successor Adrian Monk) is obsessive compulsive about order to the point of annoyance. Seeing these characters through another character in the story gives us someone we can more easily identify with.
Of course, this POV is not without it's difficulties. The main one is access to information. Things that happen outside the presence of the veiwpoint character must be inferred by other evidence or reported by the main character to the "author." Likewise, you are not privy to the thoughts of the main character except through dialog or inference based on the relationship between the two.