The proposed book consists of applied philosophical analyses of ethical issues that arise for police detectives and other investigators. Such issues include investigative independence, deception, privacy rights in the context of anti-corruption measures such as data gathering and surveillance, and the ethics of interviewing. The analyses of these ethical issues are anchored in 'reality' by reference to relevant empirical studies, actual investigations, investigative techniques, and so on. Crime and corruption are pervasive and ongoing problems that require investigation. This is obvious in relation to homicide, rape and assault. However, white collar crime in an important and growing area for investigators. For example, in monetary terms fraud is the biggest crime problem confronting the developed world. Drugs, computer crime, and organised crime require more specialised forms of investigation. Other areas for investigators include arson, sabotage, and negligence in relation to health and safety. More recently, investigative agencies, such as the FBI and the Australian Federal Police, have been preoccupied with the investigation of acts of terrorism. Notwithstanding the importance of investigative ethics, and the increasing numbers of investigators, notably in non-police areas, there is to date no book length treatment of the subject. Rather investigators and educators have to rely on generic chapters in books on, for example, police ethics, e.g., John Kleinig The Ethics of Policing (CUP, 1996), Edwin Delattre Character and Cops (AEI Press, 1994), Seumas Miller and John Blackler Ethical Issues in Policing (Ashgate, 2005), or the occasional journal article, e.g., in Criminal Justice Ethics. The book that I am proposing here seeks to fill this lacuna.