在一些案件中,有时刑侦人员会遇到棘手的问题——找不到有用的证据。在这些案件中,违法犯罪分子可能有反侦查的经验,他们抹去了留在现场的痕迹;或是抵达现场的非刑侦人员移动现场的物品,无意中破坏了留在现场的痕迹;还可能是被害人出于恐惧、羞耻等原因清洗了案发时的痕迹。 In some cases, criminal investigators sometimes encounter difficult problems - they can not find any useful evidence. In these cases, criminals may have anti-reconnaissance experience, they erased the traces left on the scene; or non-criminal officers arrived at the scene to move items, inadvertently undermine the traces left on the scene; it is also possible Is the victim out of fear, shame and other reasons when the cleaning of the traces of the incident.