Synopsis In the age of computer and Internet cyber crimes have emerged on the scence which requires special techniques of investigation and detection. The present work highlights some important issues on the topic, e.g. Finding Network Operating System and Operating System Weaknesses; Sources of leaks in LANs and WANs; Creating a Network Security Policy; Managing NDS Security; Network Services; Transmission Media and Connections; Nature of Computer Crime; Computer Fraud; Hacking Illegal Access to Computer Material; Unauthorised Modification of Computer Programs of Data: A Case Study; Piracy and Other Offences; Computer Crime--Concluding Remarks; Introduction and Background to the Data Protection Act 1998: A Case Study; Data Controllers and the Data Protection Act 1998: A Case Study; Data Subjects' Right; and Data Privacy in Telecommunications etc.