The Return of Sherlock Holmes
How we cite our quotes:
"See here, mister," said he. "I make no complaint of being man-handled in this fashion, but I would have you call things by their right names. You say I murdered Peter Carey, I say I killed Peter Carey, and there's all the difference." (Black Peter.112)
The fact that Patrick Cairns gets upset about Holmes's language and not the fact that he tackled and handcuffed him earlier is hilarious. Cairns suggests an interesting distinction between a killer and a murderer here. There's a running idea in these stories that killing is unforgivable but that murder can be potentially justified.
"I've had to do with fifty murderers in my career, but the worst of them never gave me the repulsion which I have for this fellow. [...]"
"He is the king of all blackmailers." (Milverton.1.7-9)
Holmes views blackmail as one of the worst of all crimes, possibly because of the cruel and deliberate intention behind blackmail, as opposed to some of the murder cases he's worked.
"You know, Watson, I don't mind confessing to you that I have always had an idea that I would have made a highly efficient criminal. This is the chance of my lifetime in that direction." (Milverton.1.78)
The link between detectives and criminals is highlighted again here when Holmes considers how he could have been a good criminal. Criminal behavior comes down to a matter of choice here.