Quick Answer: Emil Bessels was a German zoologist, entomologist, physician, and Arctic researcher who is best known for his controversial role in the attempted but ill-fated Polaris expedition to the North Pole in 1871. Circumstantial evidence strongly points to Bessels as the most likely suspect in the death of the expedition's commander, American explorer Charles Francis Hall, by arsenic poisoning. Bessels spent much of his scientific career at the Smithsonian Institution.