TANSOR, England -- In the land of Sherlock Holmes and Agatha Christie, it has fallen to a taxidermist to uncover whether foul play is to blame for the corpse found floating in a lake here late last month: Benson, the legendary 52-pound carp whose untimely death has captivated a nation's anglers.

For years, Benson was a catch-and-release attraction in Bluebell Lakes, a private fishing complex. Benson was a normal-size carp when she was placed in Kingfisher Lake 16 years ago. The lakes' owner, Tony Bridgefoot, noticed Benson's...