大象传媒

In March 1968 more than 6,000 sheep died while grazing close to the Dugway Proving Ground, the US military's leading chemical warfare testing site, located in the US state of Utah. One theory was that they were killed by a nerve agent. Deputy Sheriff William Pitt arrived at the scene as some of the sheep were still in convulsions. He has been telling Mike Lanchin about that strange event, which became known as the Skull Valley Sheep Kill.

Photo: Two farmers checking the corpses of dead sheep on a farm ranch, possibly connected to a chemical and biological warfare testing at Dugway Proving Ground, March 1968. (Photo by Rolls Press/Popperfoto/Getty Images)