written, produced, & directed by Iain Riddick ; produced by Ruth Roberts ; produced by Darlow Smithson Productions Ltd, Shock of Mighty Productions and Handel Productions (EFS) Inc. in association with NOVA/WGBH Educational Foundation and Discovery Channel Canada ; WGBH
a Frontline co-production with RAINmedia, Inc. ; a production of WGBH/Boston ; written and produced by Martin Smith and Marcela Gaviria ; co-produced by Will Cohen
a production of Nova and National Geographic Television in association with Duncan Copp Ltd. ; NGHT, LLC and WGBH Educational foundation ; produced and directed by Duncan Copp
produced by Mary Olive Smith and Steven Engel ; directed by Mary Olive Smith and Amy Bucher ; an Engel Entertainment production in association with Nova