In the 2011 Sherlock Holmes: A Game of Shadows,
Moriarty and Irene Adler have an brief conversation in a restaurant. After the exchange, she passes out before exiting. Later in the film, Moriarty converses with Sherlock Holmes and tells him that Irene contracted "a deadly form of tuberculosis" and presents him with a bloodied handkerchief, seemingly as proof to the claim that she is dead.
Holmes accepts the information with little doubt and then the subject is dropped entirely for the rest of the movie. My question is: why would Sherlock Holmes take his enemy at his word? Why wouldn't he investigate these claims to make sure Moriarty wasn't bluffing? Considering his relationship with Irene Adler, I thought more time would have been spent developing this plot element.