William Le Queux 
Hushed Up! [EPUB ebook] 

Excerpt:
“And he died mysteriously?”
“The doctors certified that he died from natural causes—heart failure.”
“That is what the world believes, of course. His death was a nation’s loss, and the truth was hushed up. But you, Phil Poland, know it. Upon the floor was found something—a cigar—eh?”
“Nothing very extraordinary in that, surely? He died while smoking.”