How do police find out about indecent images?
If you’ve found yourself facing indecent images accusations, you will be wondering how to defend yourself. Part of your defence will be understanding the evidence against you and how it came to light.
In this article, our expert indecent images solicitors outline the methods the police use to find indecent images online, how they trace these images back to individuals, and how they investigate thereafter.
How do police find indecent images online?
Finding indecent images online is a worldwide effort involving multiple organisations and various types of software. UK police track down some indecent images online themselves but also receive tens of thousands of referrals per year from other agencies.
Keyword and metadata monitoring
Law enforcement agencies monitor search terms, chat logs, and online forums for suspicious activity. They use special algorithms to flag certain phrases or patterns linked to CSAM (child sexual abuse material).
Web crawlers and automated scanning
Many organisations use bots called web crawlers to scan the open web for known CSAM. When images are identified, they notify the hosting providers and request the content is removed, and alert law enforcement.
Hash-matching technology
Big tech companies like Microsoft and Facebook developed hash-matching technologies to identify copies of known CSAM. Tools like Microsoft’s PhotoDNA create a unique digital fingerprint (hash) for known CSAM. When the tool finds an image with the same or similar hash, it reports it to law enforcement.
AI and machine learning classifiers
Tools like Google’s Content Safety API use AI to identify new CSAM that is not already held in the database. It flags suspicious content and prioritises it for human review, and then passes on the information to law enforcement.
Mandatory reporting by tech companies
In many places, it is mandatory for tech companies like social media platforms, email providers, and cloud storage services to send reports of suspected CSAM directly to the authorities. In the US, the National Center for Missing & Exploited Children use CyberTipline to facilitate reporting. Once the IP address has been identified, these are then routed to the relevant authority.
Dark web investigations
The dark web is not indexed by search engines and is known for its anonymous browsing. Specialist cybercrime units monitor forums, marketplaces, and peer-to-peer networks on the dark web, exploiting technical vulnerabilities to identify offenders.
Peer-to-peer (P2P) network monitoring
It is common for offenders to share images over P2P file-sharing systems. Police have software which can detect when files with known hashes are being shared.
Human intelligence and tip-offs
The police also rely on tip-offs from the general public. Friends, family, work colleagues, and even service workers like computer repair engineers can notify the police when they suspect indecent image offences have been committed.
How do police trace indecent images back to a person?
Once the police have been alerted to indecent images, they can identify the individual responsible by:
- Establishing the IP address associated with the image.
- Using powers under Regulation of Investigatory Powers Act (2000) to request subscriber details linked to that IP address from the Internet Service Provider.
- Cross-check the subscriber details against databases like the Police National Computer (PNC), electoral roll, and local intelligence systems.
The investigation is not concluded here though - they must prove that this individual actually did commit an indecent image offence.
What do police do once they trace indecent images back to a person?
With an individual identified, the police need to preserve the evidence and prove they committed the crime.
Obtain warrants
With the information gathered so far, the police obtain warrants to seize devices and search the suspects home under the Protection of Children Act (1978) or the Police and Criminal Evidence Act (1984).
Seize devices and search home
The police coordinate a visit to the suspect’s home and seize all devices that could be associated with the crime. They do further searches in the home to look for other material that could be associated with the crime.
Arrest or voluntary interview
Depending on the evidence, at this point the police may arrest the suspect or invite them for a voluntary interview at a later date. In custody or at the voluntary interview, the suspect is interviewed in a bid to gather more context to the alleged offence.
Bail and further investigation
With sufficient evidence, the suspect will be arrested at some point after the voluntary interview, if they weren’t already. Once released, they are placed on pre-charge bail to allow the investigation to go on.
The investigation involves forensic analysis of the devices. Since there is a large backlog of devices to be analysed, this could take over a year.
Charging decision
When the investigation is concluded, with enough evidence, the police seek permission from the CPS to formally charge the offender.
If they do not have enough evidence or the offender’s solicitor has put forward convincing pre-charge representations, the case may be dismissed with no further action.
What to do if you are accused of an indecent image offence?
Being accused of an indecent image offence is very serious and you must take quick action to get the best legal representation.
At Holborn Adams, we are expert indecent image solicitors. Led by Andrew Ford, a UK leading sexual offence defence solicitor (specialising in online offending), our track record of case wins is outstanding.
Make a confidential initial enquiry call today - our team is ready to help you take your next steps.
