The mass graves were discovered outside the walls of a concentration camp in PolandOne grave measures 91 feet long, while the other is 39 feetThe graves contained 19 tons of human ashes, which belonged to about 8,000 victims from the Soldau concentration campThe victims were first executed and buried, but Nazi soldiers dug them up and burned the bodies in a bid to hide the murdersOfficials unveiled a stone monument where the graves were to commemorate the thousands of victims dumped into the pits A pair of mass graves containing 19 tons of ashes of at least 8,000 individuals have...