Retrospective training topic · September 2026. Practise the method with a fictional worked example, then test your reasoning in the linked dossier.
Resolve clock disagreements by preserving each original timestamp, establishing its offset and converting events to one reference clock. Only then compare whether the resulting sequence is feasible.
A practical method
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Create columns for source, event, original time, timezone or clock error, corrected time and confidence. Keep the original record alongside the corrected value.
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Apply the error direction carefully. A clock three minutes fast must be reduced by three minutes. A slow clock must be advanced. Do not silently assume that all devices were synchronised.
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Test the corrected sequence against independent constraints such as travel duration and event coverage. Distinguish compatibility from proof of uninterrupted presence.
Worked example
A lobby clock shows 10:18 and is three minutes fast. A checkout till shows 10:17 and is two minutes slow. The corrected observations are 10:15 and 10:19. They can fit a three-minute route. That resolves the apparent ordering conflict but says nothing about unobserved movements after the transaction.
What this cannot establish
A calibration made much later may not describe the earlier clock if resets or drift occurred. A transaction is one event, not continuous surveillance.
Your analyst checklist
- Preserve the original record and its provenance.
- Separate observed facts from interpretations and missing information.
- Test at least one competing explanation against the same evidence.
- Record the source and limitation beside each conclusion.
- State what additional record could change the assessment.
Practise with a fictional dossier
Operation Duplicate Alibi: Reconcile the Witness Clocks develops clock correction and corroboration. Read six synthetic evidence records, test five short-answer objectives and use progressive hints if needed. The article explains the method without giving the case’s graded answers.
Open the related case · Explore the Case Vault
Frequently asked questions
Should I overwrite the original time?
No. Preserve it and add a clearly labelled corrected value.
Does a feasible route prove an alibi?
No. Feasibility removes one contradiction; a complete alibi needs appropriate coverage.
What if the offset is unknown?
Keep an uncertainty interval or mark the time unresolved instead of inventing a correction.