Investigative Techniques: Planning, Interviews, Surveillance and Open-Source Work
Method before motion
Sound investigation begins with a scoped retainer: what question must be answered, what is the lawful basis for each step, and what will not be done. Candidates should understand evidence-led planning - identify the allegation, list the facts needed to prove or disprove it, then choose the least intrusive technique that will yield them. Techniques include records and open-source research, interviews, scene examination, and surveillance.
Interviews
Know the difference between an interview (voluntary, information-gathering) and an interrogation (accusatory, generally police territory). Investigators must not detain, must make clear the person may leave, and must avoid promises, threats, or misrepresenting their authority. Record the who, what, when, where, and how of the conversation, note the person's demeanour factually, and never put words in the subject's mouth.
Surveillance and open source
Surveillance must occur from public places where there is no reasonable expectation of privacy; trespass, peering into homes, and intercepting private communications are off-limits. Open-source research is lawful but must be documented: capture the source, date, time, and a faithful copy, because pages change. Do not use deception to obtain private account access.
Traps
Questions test overreach: pretexting as an insurer or bank, impersonating a government official, or claiming a duty to answer questions. Another trap is treating a hunch as a technique - undocumented steps cannot be defended.
Worked example
A subject is suspected of working while claiming disability. Rule of thumb: observe from public space, record only what is visible from there, and log date, time, location, and duration for every observation. Anything requiring entry onto private property needs a lawful basis the investigator can name.