The Germans destroyed much of the camp's files and evidence and often allocated newly arrived prisoners the camp numbers of those who had already been killed, so the exact death toll of Mauthausen and its subcamps is impossible to calculate. The matter is further complicated due to some of the inmates of Gusen being murdered in Mauthausen, and at least 3,423 were sent to Hartheim Castle, away. Also, several thousands were killed in mobile gas chambers, without any mention of the exact number of victims in the remaining files.