杀人不见血

Explanation: Murder do not reveal a trace. Described as a very sinister and ruthless means of harm. 　　Usage: Complex sentence; as attribute, clause; containing derogatory 　　Source: Ming Feng Meng, "Awaken the common saying": "That is called Li Li Linfu Hunming cat, Pingxi bad I do not know how many ministers, but subtle and underhanded executioner." Thesaurus:  kill without batting an eye lid, kill without blinking an eye