How should investigators convert times safely?¶

Preserve the timestamp exactly as received, establish its source and time zone, then apply a date-specific conversion and document the result. A fixed mental adjustment is unsafe where daylight-saving or historical zone rules may apply.

A defensible conversion retains its inputs¶

Record the original value and any suffix or offset such as Z, +00:00 or +01:00. Establish whether the field contains UTC, a fixed offset, a named local zone or merely a display value, and whether it represents source, receipt or ingestion time.

Use a recognised zone database or conversion tool that applies the rules in force on the event date. Named zones matter because jurisdictions change clocks on different dates and historical rules can differ from current ones.

Keep an auditable conversion record¶

For each material conversion, retain the original value and zone, target zone, converted value, tool or rule source and any assumptions. Converting a working timeline to UTC can aid comparison, but the source values must remain available.

If the original zone is unknown or a repeated daylight-saving hour has two interpretations, do not select one silently. Report the alternatives until configuration, provider documentation or an independent record resolves them. Check exports and spreadsheets for automatic reformatting as well.