Resources · Guide
How to preserve CCTV evidence
To preserve CCTV evidence, secure a native export of every relevant camera as soon as possible, before the recorder overwrites it. Keep the player software, photograph the recorder’s clock, and never film the screen or convert the file. This guide sets out each step.
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7–30 days
Many CCTV recorders automatically overwrite footage within 7 to 30 days, and some much sooner. Start today, even if you are not sure the footage will be needed.
Why you need to act quickly
Most CCTV recorders store footage on a hard drive that records in a continuous loop. When the drive is full, the oldest footage is automatically overwritten, often within 7 to 30 days and sometimes within hours on busy systems. Once it has been overwritten, it usually cannot be recovered.
Footage can also lose evidential value long before it is overwritten. Filming the screen, converting the file or sending it through a messaging app removes detail, timing information and metadata that a forensic examiner relies on. Preserving the evidence properly from the start keeps every option open.
Eight steps to preserve CCTV
Follow these steps in order. If you can only do one thing today, ask the system owner to export or protect the footage before it is overwritten.
Identify every relevant camera and the time window
List each camera that may have recorded the incident, including cameras on neighbouring premises and in car parks. Ask for footage from well before to well after the incident, not just the moment itself.
Stop the footage being overwritten
Ask the system owner to export the footage immediately, or to protect, lock or bookmark the relevant period on the recorder. If that is not possible, ask them to note the date and time when the footage will be overwritten.
Photograph the recorder’s clock
Take a photo of the recorder’s on-screen time next to a reliable clock, such as a mobile phone. This lets the recorder’s clock error be measured later. Do not change the clock setting.
Export in the native format
Use the recorder’s own export function and choose its native or original format, not MP4 or AVI conversion. Export every relevant camera, and include any player software the system offers.
Record the system details
Note the make and model of the recorder, the number of cameras, where each camera is positioned and who carried out the export. Photos of the recorder and each camera are helpful.
Verify and keep a second copy
Check that the export plays, then make a second copy on separate media. Keep the original export exactly as it is, without renaming, trimming or re-saving the files.
Document how the footage was obtained
Write down who exported the footage, when, from which system and onto what media, and who has held it since. This record supports the chain of custody.
Contact a forensic expert before sending
Call us before sending anything, so we can arrange a secure transfer and advise on anything still to be collected. Never send evidence by messaging app or ordinary email.
What not to do
These common mistakes can permanently reduce what the footage can show:
- Film the monitor or screen with a phone instead of exporting the footage
- Convert the export to MP4 or another format before sending it
- Send footage by WhatsApp, Messenger, social media or ordinary email
- Trim, rename or re-save the exported files
- Change the recorder’s clock, or move or adjust the cameras
- Rely on someone else’s copy if the original recorder still holds the footage
If a screen recording or converted copy is all you have, keep it anyway. It can still be assessed, and it may help identify which camera and time period to request from the original system.
Dashcam, doorbell and phone video
The same principle applies to every source: keep the earliest, most original version of the file, exactly as it was recorded.
| Source | What to keep |
|---|---|
| DVR or NVR recorder | The native export from every relevant camera, with the player software and any extra files the export creates. |
| Cloud or doorbell camera | The original clips downloaded from the app or website, before the subscription retention period deletes them. |
| Dashcam | The whole memory card, removed from the camera and stored safely, rather than single clips copied from it. |
| Mobile phone video | The original file transferred from the phone by cable or cloud backup, not a version sent through a messaging app. |
| Body-worn camera | The export from the evidence management system, together with its audit trail. |
Requesting footage from others
If the footage belongs to a business, council, transport operator or other organisation, ask in writing as soon as possible. Give the exact location, the date and a time window, and ask them to preserve the footage even if they cannot release it straight away.
Ask for the native export rather than a converted copy, and for the player software. Police and public bodies may require a formal request or subpoena, so lawyers should consider a preservation request early. Note who you asked, when, and what they said.
Not sure what you have, or whether it can still be saved? Contact us and we will advise on the fastest way to secure it. You can also read how proprietary exports are decoded and how CCTV footage is analysed.
Printable checklist
CCTV evidence preservation checklist
A one-page version of this guide to print or send to whoever is collecting the footage.
Frequently asked questions
Preserving CCTV FAQs
Answers to the questions we are asked most often about securing CCTV footage.
See all FAQsAs soon as possible. Many recorders overwrite old footage within 7 to 30 days, and some much sooner. Ask the system owner to export or protect the footage straight away, even if you are not yet sure it will be needed.
The recorder’s native or original format, together with any player software it offers. Converting to MP4 or another format can drop frames, change timing and remove metadata.
It is the weakest form of CCTV evidence. Filming a screen adds glare and distortion and loses the original timing and metadata. Keep it if it is all you have, but obtain the native export if the recorder still holds the footage.
Usually not. Once a recorder has written over footage, it is very rarely recoverable. That is why securing an export, or asking the owner to protect the footage, is the first priority.
Contact us first. We will provide an encrypted transfer link, or arrange for the original media to be collected by courier. Do not send evidence by messaging app or ordinary email.
Not always. Many businesses will release footage on request. Police, councils and some organisations may require a formal request or subpoena, and a lawyer can send a preservation request early.
Get expert advice
Footage at risk of being overwritten?
Call us now. We will tell you the fastest way to secure it, what to ask the system owner for, and how to send it to us safely.
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Monday to Friday, 9.00 am to 5.30 pm
All enquiries are treated in strict confidence. Please contact us before sending any footage so we can advise on the most appropriate transfer method. If you do share footage with us, always use a secure method to protect the integrity of your evidence.