Criminal Investigation Methods: Evidence, Interviews and Case Files Training Course

Programme Summary

Criminal investigation methods are the subject of this one-week training course for senior managers who direct investigations, ending in a case file review pack for one live inquiry. Heads of investigation units answer for lines of enquiry, evidence handling, interviews and the quality of files that reach prosecutors. The programme moves from scene and evidence control to interviewing, digital material and case file assembly, using examples from policing, corporate security and regulatory inquiries. Mars Training Centre UK delivers this programme on criminal investigation methods to mixed-organisation cohorts.

The Business Case

Investigations fail late and quietly: a scene left uncontrolled, an interview that cannot be relied on, a gap in the record of who held an exhibit, or a file that leaves the prosecutor with open questions. Unit heads see these risks earliest, yet rarely share a method for testing them. A consistent approach to evidence and review lets decisions be explained to courts, oversight bodies and boards.

• Case Quality: Improves as files are reviewed against one standard before they leave the unit.
• Evidence Integrity: Strengthens as every exhibit and digital item stays traceable from recovery to court.
• Decision Defensibility: Rises as lines of enquiry and interview choices are recorded with reasons.

Principles and Evidence Base

• PEACE Interview Model: Structures planning, engagement, account, closure and evaluation of interviews, applied in Sessions 2 and 3.
• ISO/IEC 27037 Guidelines for Digital Evidence: Frames identification, collection, acquisition and preservation of digital material, applied in Session 4.
• Chain of Custody Logic: Requires each exhibit to be traceable through every hand that held it, applied in Sessions 1 and 5.
• Hypothesis Testing Logic: Treats each line of enquiry as a proposition to be confirmed or ruled out by evidence, applied in Sessions 2 and 5.

Intended Participants

• Managers who direct investigation units and set the lines of enquiry for serious cases.
• Senior police and security officials who review inquiry files before they reach prosecutors.
• Legal and compliance directors who rely on investigation findings for decisions and referrals.
• Leaders of corporate and regulatory inquiry teams who commission interviews and evidence recovery.
• Heads of function who sponsor internal investigations and must judge how reliable they are.

Typical settings include police services, corporate security departments, financial regulators and public bodies with inquiry functions.

Learning Outcomes

1. Participants will be able to construct a scene and exhibit control plan that preserves a complete chain of custody.
2. Participants will be able to prioritise lines of enquiry and test each one against the evidence held.
3. Participants will be able to evaluate a witness account for reliability and gaps before it is relied on.
4. Participants will be able to design a suspect interview plan using the PEACE interview model.
5. Participants will be able to diagnose weaknesses in digital, documentary and financial evidence handling.
6. Participants will be able to justify a case file for submission to prosecutors from a structured review.

Programme Structure

Day 1: Scene Control and Evidence Integrity

How is a scene secured and recorded so that every exhibit can later be traced?

• Scene Cordon and Access Log
• Exhibit Recovery and Labelling Standard
• Chain of Custody Register
• Scene Photography and Sketch Record
• First Responder Handover Brief

Day 2: Lines of Enquiry and Witness Accounts

How are lines of enquiry set and tested, and how are witness accounts taken reliably?

• Hypothesis and Line of Enquiry Matrix
• Enquiry Plan and Task Allocation
• Witness Account Planning Sheet
• Open Question Prompt Set
• Account Reliability Check

Day 3: Suspect Interviews Using the PEACE Model

How is a suspect interview planned, conducted and evaluated so that the record stands up?

• PEACE Interview Planning Sheet
• Disclosure Decision Log
• Question Sequence and Challenge Plan
• Interview Record Standard
• Interview Evaluation Form

Day 4: Digital Material, Documents and Financial Trails

How are digital and documentary sources identified, preserved and weighed?

• ISO/IEC 27037 Handling Stages
• Device Seizure Checklist
• Document and Records Request Plan
• Financial Trail Map
• Evidence Source Reliability Grid

Day 5: Case File Review Pack for One Live Inquiry

Does the file give a prosecutor a complete, consistent and tested case?

• Applying the Session 1 Chain of Custody Register
• Testing the Session 2 Line of Enquiry Matrix
• Reviewing the Session 3 Interview Evaluation Form
• Checking the Session 4 Source Reliability Grid
• Completing the Case File Review Pack

Methodology

The programme uses a structured exercise built on one prepared inquiry, with scene records, witness accounts, interview transcripts, device extracts and a draft file. Participants make each decision, record the reason in a common format and compare results in small groups before applying the same tools to an inquiry from their own unit.

• Suggested activity: Ranking competing lines of enquiry and recording why one is closed.
• Suggested activity: Planning a suspect interview and critiquing a sample record.
• Suggested activity: Tracing a break in the chain of custody and proposing a remedy.

Capstone Output

Each participant completes a case file review pack for one live inquiry. It holds a chain of custody check, a line of enquiry matrix, an interview evaluation, a source reliability grid and a list of gaps with owners and dates for closing them. The pack is used at work to brief the team and to test files before submission.

Frequently Asked Questions

Is criminal investigation methods training suitable for managers who have not led an inquiry?

Yes. Criminal investigation methods are taught through a worked inquiry. The training assumes exposure to investigations or to the review of their files, but no forensic science or legal background.

Which references does criminal investigation methods training rest on?

Criminal investigation methods training rests on the PEACE interview model and ISO/IEC 27037 for digital evidence, together with chain of custody logic and hypothesis testing logic for the case file.

How is the case file review pack from criminal investigation methods training used at work?

You use the case file review pack to brief your team, test files before they go to prosecutors, and show how each evidence and interview decision was made.

How do criminal investigation methods differ from fraud investigation training?

Criminal investigation methods training covers scene control, interviews and prosecution files across offence types, while fraud investigation training concentrates on financial schemes and loss tracing.