Criminal Investigation and Case Build-Up
Investigative process
Criminal investigation is a systematic search for truth: identify, collect, preserve, and present evidence. A sound case build-up starts with the first responder securing the scene, separating witnesses, and recording the initial account. Then investigators establish the 5Ws and H, canvass for witnesses and CCTV, collect physical and digital evidence, conduct lawful interviews, and develop a case theory tested against evidence. Documentation must be contemporaneous: scene logs, photographs, sketches, inventory, chain of custody, and request forms. Coordinate with the prosecutor early, but do not surrender investigative judgment. A case folder should show what is known, what is inferred, and what remains unverified.
Traps
Common failures are scene contamination, unrecorded entry and exit, moving objects before photography, interviewing witnesses together, promising confidentiality without basis, and treating a suspect's silence as guilt. Avoid conclusions before evidence is analyzed; avoid coercive or suggestive interviews; avoid illegal searches and seizures. An affidavit should distinguish personal knowledge from information received. Do not omit exculpatory evidence. Do not confuse probable cause for filing with proof beyond reasonable doubt.
Worked example
In a burglary, preserve the point of entry, photograph and sketch the scene, collect latent prints and DNA where relevant, secure CCTV, canvass neighbors, and record each transfer of evidence. Rule of thumb: investigate from the scene outward and document as you go. If it is not in the case folder, it may not exist at trial.