Introduction 15 Purpose and structure of the manual This present manual focuses on the investigation process and has been produced following requests from law enforcement officers working in the field for a practical tool to aid their work. It is designed to help improve democratic policing practice across the OSCE and to assist law enforcement practitioners in strengthening their compliance with OSCE commitments and international human rights standards in the investigation of terrorism-related crimes. It is intended to be both a stand-alone tool and a complement to ODIHR’s Countering Terrorism, Protecting Human Rights manual and training programme, which approaches the subject from a legal standpoint. This present manual, rather, examines the topic from an operational and practical point of view. Therefore, the law will not be quoted in great detail, but there will be frequent reference to the relevant legal standards as set out in Countering Terrorism, Protecting Human Rights in order to avoid duplication. The two manuals can be used together by those wishing to further explore the subject. The manual deals with the policing issues faced by those tasked with the difficult and sensitive job of investigating terrorism-related offences. It applies human rights standards and laws to those issues, using real-life examples that have tested law enforcement agencies in OSCE participating States. The chapters follow, as far as possible, the same sequence that investigations usually follow, using both pro-active and reactive methods of investigation, although real life rarely allows for a neat distinction between the two. Thus, it examines intelligence gathering (including the use of technical surveillance, the interception of communications and the physical surveillance of suspects and suspect premises), before addressing other issues, such as crime scene examination, dealing with witnesses, detaining and questioning suspects, accountability and the security of investigations. Related subjects, such as international co-operation and extradition, are discussed at the appropriate stages. Its primary target audience is law enforcement personnel working on counterterrorism issues and prosecuting authorities supervising or involved in the prosecution of terrorism-related offences. However, those involved in combating organized crime will also find much that is relevant to their work, considering the similarities in law enforcement tactics to counter these two areas of criminality. The manual gives general guidance about what law enforcement officers should and should not do and what the consequences of their actions may be. Case studies are used throughout the manual to illustrate practical