Spanish authorities have arrested the 3 key people behind the Mariposa Botnet, but the mastermind is still unknown. The Mariposa or buttlerfly Bot (Mariposa is Spanish for butterfly) was shut down by authorities in December of 2009. The Bot had infected around 12.7 million machines in more than 190 countries.
This Botnet, like Kneber was used to steal account and login information. It is estimated that half of the Fortune 1000 companies had machines that were infected. The group running Mariposa was called the DDP (Días de Pesadilla or Nightmare Days) Team. For more information see The Register article, “How FBI, police busted massive botnet“.