Mobile phones can contain important evidence in drug investigations. Text messages, WhatsApp chats, photographs, contact lists, call records and other digital material may help investigators build a picture of communications and events. That does not mean that every message automatically proves a criminal offence. The relevance, authenticity, context and meaning of digital evidence all matter.
The CPS recognises communications evidence as potentially important material in criminal investigations. Investigators may examine devices and other digital sources where this is a reasonable line of enquiry. Relevant material can include messages between suspects and third parties, as well as other communications that may support or undermine an allegation.
What can messages show?
In a drug case, communications might be relied upon to suggest discussions about drugs, money, meetings, transport or other arrangements. Timing and frequency can also be relevant. Investigators may compare messages with phone records, CCTV, location information, financial transactions and witness accounts.
However, messages can be ambiguous. Slang, abbreviations, jokes, sarcasm and incomplete conversations can create difficulties when individual messages are taken out of context. A message may also have been sent by someone other than the person alleged to have used the account. The CPS guidance recognises the importance of examining digital material properly and considering relevant material that may assist the defence as well as the prosecution.
Can deleted WhatsApp messages be recovered?
Digital investigations can involve forensic extraction and analysis of devices or other sources. Whether particular deleted material can be recovered depends on the device, application, data and technical circumstances. It should not be assumed that deleting a message removes all potential evidence, but neither should it be assumed that every deleted message will be recoverable.
How can digital evidence be challenged?
Issues can include whether the correct device or account was linked to the defendant, whether the material is complete, whether messages have been properly interpreted and whether the evidence was obtained and handled appropriately. The defence may also need to identify messages or other material that provides important context or undermines the prosecution case.
The CPS has specific guidance on digital material and disclosure. Police and prosecutors have duties concerning relevant material, including material that may assist the defence. This makes the wider digital download potentially important, rather than only the few messages highlighted by the prosecution.
If you are arrested in a drug case, do not assume that a phone search will produce only evidence against you. Digital material can sometimes contain context that changes how a conversation is understood. Obtain independent legal advice before making decisions about the case.
This article is general information for England and Wales and is not a substitute for advice on the facts of a particular investigation.