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CCTV & DVREVIDENCE · A GUIDE FOR UK LAWYERS Recovering Deleted CCTV and DVR Footage The Overwrite Clock, the Proprietary Recorder and the Race to Preserve the Frame COMPUTER FORENSICS LAB
§ ABOUT THE AUTHOR PREPARED BY COMPUTER FORENSICS LAB E-DISCOVERY TEAM PROPRIETARY-FORMAT DECODING CPR PART 35 EXPERT REPORT S FULL CHAIN-OF-CUSTODY DOCUMENTATION
§ CONTENTS In this guide 01 Executive summary 02 The problem in plain English: footage that overwrites itself 03 How DVR and CCTV systems store and overwrite footage 04 Preserving before the loop: the urgent first steps 05 Recovering deleted and overwritten footage 06 Formats, timestamps and authenticity 07 Deployment: disclosure, the lost frame and the filmed monitor 08 Source architecture: where else the evidence lives 09 Worked examples 10 Common mistakes and technical limitations 11 Questions to ask · Suggested wording 12 Checklist and red flags · When to involve a digital forensic expert 13 Frequently asked questions 14 Glossary · References · Disclaimer · How a specialist laboratory can assist
§ 01 · ORIENTATION Executive summary weeks: preservation is the emergency, it comes before analysis, and the single most important act is to secure the recording, or the whole recorder, before the loop erases it.
§ 02 · FIRST PRINCIPLES The problem in plain English: footage that overwrites itself
§ 03 · HOWITSTORESFOOTAGE How DVR and CCTV systems store and overwrite footage CAMERAS RECORDER RING BUFFER OVERWRITE PRESERVE FIRST
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§ 04 · PRESERVINGBEFORETHELOOP Preserving before the loop: the urgent first steps
§ 05 · RECOVERINGDELETEDANDOVERWRITTENFOOTAGE Recovering deleted and overwritten footage
§ 06 · FORMATS, TIMESTAMPSANDAUTHENTICITY Formats, timestamps and authenticity
§ 07 · DEPLOYMENT Deployment: disclosure, the lost frame and the filmed monitor
§ 08 · THEWIDERMAP Source architecture: where else the evidence lives EVIDENCE OVERLAPPING CLOUD COPY PRIMARY EXPORTED RECORDER DELETED / RECORDER CLIPS LOGS RECOVERABLE OTHER / CAMERAS
§ 09 · IN THE WILD Worked examples EXAMPLE1 · THEFOUR - DAYRETENTIONANDTHEONEDAYLEFT EXAMPLE2 · THEDELETEDFOOTAGECARVEDBEFORETHELOOPCAUGHTIT EXAMPLE3 · THEFILMEDMONITORANDTHENATIVEFILETHATREPLACEDIT
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§ 10 · WHEREITGOESWRONG Common mistakes and technical limitations Common mistakes Technical limitations
§ 11 · INTERROGATORIES & DRAFTING AIDS Questions to ask · Suggested wording Ask your client Ask your opponent (or a third-party holder) Ask your e Discovery / forensic provider SUGGESTED WORDING · URGENTCCTVPRESER VAT I ON REQUEST
§ 12 · QUICK CONTROL Checklist and red flags · When to involve a digital forensic expert The CCTV / DVR checklist Red flags When to involve a digital forensic expert
§ 13 · COMMON QUESTIONS Frequently asked questions How long do we have before CCTV footage is gone? Can we just film the CCTV monitor on a phone? Footage was deleted from the DVR. Can it be recovered? The timestamp on the footage looks wrong. Does that matter? The footage is dark or blurry. Can it be enhanced? The other side let the footage overwrite. Is there anything we can do?
§ 14 · REFERENCE Glossary NVR Sources and authoritative references DISCLAIMER
§ HOW A SPECIALIST LABORATORY CAN ASSIST Working with Computer Forensics Lab Speak to a forensic examiner, not a salesperson. INSTRUCTTHELAB NEWENQUIRIESEMAILE - DISCOVERY
Cite as: Joseph Naghdi, Recovering Deleted CCTV And DVR Footage, Computer Forensics Lab, https://e-discovery.uk/library/recovering-deleted-cctv-and-dvr-footage/pdf.