Principles, including the principle of felony, necessity, pertinence and examination and approval, should be persistingly followed in application of technical investigation to official crimes.

• 技术侦查的种类一般包括麦克风侦听、电话侦听、窥视监控、邮件检查、外线侦查等。技术侦查主要有以下特点:(一)秘密性。