Lucius was sitting with Amelia Bones going over the reports from the last war and they found a complete mess with the investigation and as a result a disaster. During the war, the order that Dumbledore had founded against Voldemort was more a liability than helpful for the auror department since the arrests of civilians was not legal and the evidence was basically compromised. Many death eaters used the excuse of the imperious or that those, who arrested them, were prejudiced against them since they were coming from dark families or were members of the Slytherin house, which was a setback and allowed the death eaters to escape justice. The only arrests that were legal were done by the aurors of the order, but with the rest, the death eaters were able to bribe their way out of Azkaban by claiming the imperious or the prejudice, apart from Lucius.