I find this book very challenging because of the specific words used in the story - some that I learned this year through a vocabulary book, and others that I simply assume is what it is. So far, I find the book confusing - there's no one that I am 100% clear as for the culprit, and I am halfway towards finishing.
So far, I am predicting many assumptions - one that the culprit to Sir Charles' death is the workers who left the mansion because of such. I say this because, first, the fact that they've served for generations and are already prepared to leave is a huge factor; plus, the fact that they want to leave afterward may be because they've tainted their hands in Sir Charles' blood.
Another assumption is Sir Henry of the Baskervilles, which I find surprisingly suspicious as well. It was possible that he killed Sir Charles himself to gain his position as master, and acting innocently in order to remain safe from Sherlock Holmes's hands.
Lastly, my least favorite assumption is Dr.Mortimer. Similar to Sir Henry, it may be possible that he killed him and is helping Sherlock Holmes playing innocent.
What a mystery! Who knows what it'll be.