Investigations must adhere to principals of respect for human rights, legal procedure, and appropriate methodology. Every investigation should include a preliminary investigation, informal developments, human factors, prioritization, case supervision, investigator selection, and knowledge of the rules of evidence. The who, what, when, where, why, and how are important parts of any investigation. General topics covered include the crime scene, investigation procedures, informants, and testimony. Undercover operations, arrest, and forensics are detailed. Guidance is also offered for specialized investigations, such as property crime, vehicular crime, organized crime, check and credit card fraud, fencing, and terrorism.