Eyewitnesses included British POWs who were part of the forced labor that built the camp , and Dr. StanisÅ aw Byczkowski , head of the Department of Toxicology at the GdaÅ sk School of Medicine . Eyewitnesses included British POWs who were part of the forced labor that constructed the camp , and Dr. StanisÅ aw Byczkowski , head of the Department of Toxicology at the GdaÅ sk School of Medicine .