Searches, Samples, Fingerprints and Digital Devices

1. The investigation does not stop while the interview takes place

An interview is only one way of obtaining evidence. During the same period, officers may search premises, secure clothing, take fingerprints or samples, arrange an identification procedure, seize devices and compare material with police databases. The account given in interview may later be tested against evidence that neither the client nor the interviewing officer has yet seen.

That changes the defence task. It is not enough to prepare what the client may say. The solicitor must understand what other evidence is being sought, what it is capable of proving and which urgent safeguards are required while the client is detained.

2. The authority-and-evidence audit

1. Act. What exactly is proposed: a search, seizure, photograph, fingerprint, sample, identification procedure, extraction, password request or formal notice?
2. Authority. Which power is relied upon, who authorised it and have its conditions been met?
3. Scope. What person, place, item or data may lawfully be examined, and for what purpose?
4. Consent. Is agreement legally required? Can the step proceed without it? What may follow from refusal?
5. Evidence. Which proposition is the procedure intended to test, and could the result include or exclude the client?
6. Safeguard. Are dignity, vulnerability, privilege, confidentiality, third-party data or business continuity engaged?
7. Record. What was requested, explained, authorised, taken, copied, refused or agreed?
8. Review. What result, return, access arrangement or legal challenge should follow, and when?

3. Searches of the detainee

On arrival at a police station, the custody officer must ascertain what property a detainee has. Property may be retained where the statutory conditions apply, including because it may be evidence or may create risks within custody. The power is not a licence for unnecessary intrusion.

Ordinary property and clothing searches

The object may be to record possessions, protect safety or preserve evidence. Clothing can itself carry blood, fibres, glass, soil, drugs, biological material, residue, damage or an identifying feature. The record should distinguish property held for safekeeping from material seized as evidence.

Strip searches

A strip search involves removal of more than outer clothing. It is not routine custody administration. Code C requires necessity, proper authority, privacy, respect for dignity and detailed safeguards about who may be present and how the search is conducted. The reason and conduct should be recorded. Vulnerability, age, health and communication needs may be decisive.

Intimate searches

An intimate search is a physical search of a body orifice other than the mouth. It is governed by a narrow statutory regime and may be undertaken only for specified objects and under specified authority and safeguards. It should never be described to the client as merely the next level of an ordinary search. Immediate legal and, where required, healthcare involvement is essential.

4. Searches elsewhere after arrest

An arrest may trigger a search at home, work or another location. A warrant is one route. PACE section 32 may permit a limited search of premises where a person was arrested or was immediately before arrest when the statutory conditions are met. Section 18 may permit a search of premises occupied or controlled by a person arrested for an indictable offence for evidence relating to that offence or a connected or similar indictable offence, ordinarily with inspector-level written authority, subject to statutory exceptions.

The power defines the premises, purpose and objects of the search. Under Code B, officers should search only so far as reasonably required by that purpose, cause no more disturbance than necessary and stop when the object has been achieved or they are satisfied the item is absent. The size and nature of what is sought matter: a stolen vehicle cannot be in a drawer; a memory card can.

The detainee may know almost nothing about the search. The solicitor should establish, where practicable, the asserted power, premises, time, occupants present, items sought, material removed, comments made and whether a search record has been supplied. A major business, journalistic or privilege issue may require a second lawyer outside the police station.

5. Seizure is not the same as unlimited examination

A lawful search power may permit seizure of material within its terms. PACE and the Criminal Justice and Police Act 2001 also contain powers permitting material to be removed for examination or sifting elsewhere where relevance cannot reasonably be determined on site. Those powers matter in document-heavy and digital investigations, but they do not erase questions of scope, relevance, excluded material, special procedure material or legal professional privilege.

For every item removed, the defence should distinguish: ownership; where and from whom it was taken; the seizure power; the evidential purpose; whether a copy was made; and whether continued retention remains necessary. Police possession does not prove incrimination. It proves only that officers considered the item capable of falling within a power of seizure.

6. Legal professional privilege

Communications protected by legal professional privilege are not ordinary evidence. The protection belongs to the client and is not lost merely because privileged material sits beside non-privileged data. Difficult cases arise where a phone, laptop, mailbox or document set contains mixed material that cannot be separated during the search.

The physical device may sometimes be lawfully removed under a seize-and-sift power even though it contains privileged material. That does not authorise investigators to read or use the privileged content. The protection must be made operational through segregation and a defensible filtering process.

• Identify the legal matter, relevant lawyer and likely dates or folders as precisely as circumstances permit.
• State the privilege claim without volunteering the substance of the advice.
• Ask what independent search, filtering or review protocol will be used.
• Require disputed material to be isolated pending resolution.
• Record the objection, the response and any undertaking given.

7. Fingerprints, photographs and identification procedures

PACE permits fingerprints and photographs to be taken in defined circumstances, sometimes without consent. The client should be told what is being taken, why and under which condition. Reasonable force may be available for some non-consensual procedures, but the existence and use of that power must not be assumed.

The meaning of the result remains contextual. A fingerprint may show contact with an object; it does not by itself prove when, why or with what knowledge the contact occurred. A photograph may record identity, injury, clothing or a distinctive feature. The evidential proposition must be separated from the scientific or visual match.

Where a witness claims to identify a disputed offender, Code D may require a formal procedure. Video identification is common, but other methods remain available. The defence should preserve the first description and assess opportunity to observe, distance, lighting, duration, stress, familiarity, delay, prior exposure to images and fairness of the procedure. Confidence is not the same as reliability.

8. Intimate and non-intimate samples

PACE separates intimate from non-intimate samples because the authority, consent, person taking the sample and consequences of refusal differ.

Intimate samples

Intimate samples include blood, semen, urine, pubic hair, dental impressions, tissue fluid and specified swabs from intimate areas or body orifices other than the mouth. The statutory definition and the circumstances of the proposed sample should be checked rather than inferred from ordinary language. Appropriate authorisation and written consent are generally required. Except for urine, samples must be taken by an appropriate healthcare professional; dental impressions are taken by a registered dentist.

Where the statutory conditions are satisfied, refusal without good cause may later support an inference. The person may therefore retain the physical choice to refuse while facing a possible evidential consequence. Capacity, understanding, health, the stated purpose and any good cause must be addressed before advice is given.

Non-intimate samples

Non-intimate samples include saliva, hair other than pubic hair, nail material, non-intimate swabs and skin impressions other than fingerprints. They may be taken with consent or, where PACE conditions apply, without it. The route should be identified. A familiar mouth swab can produce a DNA profile capable of inclusion, exclusion and database comparison.

The defence should not assume the result will harm the client. An objective sample may disprove contact or identify another contributor. The question is what proposition the comparison is designed to test and whether the analysis can answer it reliably.

9. Retention of biometric material

The rules governing retention, database searching and destruction of fingerprints, DNA profiles and samples are technical. The answer may depend on the offence, age, previous record, whether the person is charged, the outcome, a qualifying national-security determination and other statutory exceptions. The safe public guidance is not that material will automatically be destroyed if no charge follows. The individual position must be checked against the applicable regime and outcome.

10. A device is not a single piece of evidence

A telephone may contain messages, images, location history, financial records, search activity, health data, professional communications, authentication tokens, cloud links and information belonging to others. Investigators may use it to reconstruct chronology, relationships, knowledge, movement, planning and benefit. That evidential richness is also why the legal questions must remain separate.

1. Was the physical device lawfully seized?
2. What locally stored data may be examined under that authority?
3. Is remote or cloud material sought, and by which legal route?
4. Who owned, possessed, controlled and actually used the device or account?
5. Does it contain privileged, confidential or third-party information?
6. Is access being requested voluntarily or under a formal compulsory process?
7. What date range, applications, search terms and data categories are relevant?
8. How will extraction completeness, continuity and interpretation be tested?

11. Ownership, possession, control and use

The question “Is this your phone?” may be used to support several later inferences. Those inferences do not necessarily travel together. A company may own a handset; an employee may possess it; several people may know the code; one person may operate a particular account. A family device may be shared. A cloud account may be accessed from several devices.

The client should answer factual questions accurately but should not adopt a compressed label that conceals a material distinction. Attribution may require account records, device artefacts, typing patterns, location, usage history and surrounding context, not simply the place where the item was found.

12. Passcodes, encryption and biometric access

An officer may ask for a passcode. A request is not itself proof of a power to compel an immediate answer. Investigators may in an appropriate case seek a notice under Part III of the Regulation of Investigatory Powers Act 2000 requiring disclosure of protected information or a key. Non-compliance with a valid notice may be a separate offence. The notice, statutory conditions, required information, deadline, ability to comply and secrecy provisions require careful advice.

A request to use a fingerprint or face to unlock a device should likewise be treated as a distinct proposed act, not informal custody administration. The client should not volunteer assistance merely because the technology makes it quick. Nor should the client be advised that resistance is necessarily lawful or effective. The officer should identify the asserted authority; specialist advice may be required immediately.

13. Voluntary extraction from an electronic device

A separate statutory code governs authorised persons who obtain information from an electronic device through the agreement of a user, commonly in investigations involving complainants or witnesses. Agreement must be informed and may be withdrawn before extraction. The person should be told the purpose, what information is sought, how it will be obtained and used, and that refusal does not itself end the investigation.

That consensual regime should not be confused with examination of a suspect device already seized under another power. In either setting, necessity and proportionality require precision. “Everything on the phone” is not a substitute for identifying the relevant data, period and investigative purpose.

14. Digital evidence is objective material interpreted by people

A forensic extraction can be technically accurate and evidentially misleading. The defence may need to ask which device and account were examined; whether extraction was logical, file-system or physical; what was omitted; how timestamps and time zones were handled; whether content was created, received, cached, downloaded or synchronised; whether a message was sent, drafted, forwarded or deleted; and who was using the account.

A selected message is a fragment. Its words may be fixed while its meaning remains disputed. The surrounding thread, earlier events, attachments, participants and later conduct may transform the inference. Context does not neutralise incriminating words by magic. It tests what those words actually referred to and whether the proposed interpretation is reliable.

15. Deletion, remote access and preservation

Deleted material may remain recoverable through application databases, thumbnails, caches, backups, logs or other devices. Investigators may treat deletion after awareness of an investigation as concealment or interference. Yet deletion is not inherently criminal: applications purge data automatically and people delete material routinely. Timing, mechanism, settings and purpose matter.

Once an investigation is known, preservation should replace instinct. The client should not remotely wipe a device, delete messages, change settings, ask another person to remove material, dispose of linked devices or access an account in a way that changes evidence. Equally, the client should not begin a self-directed forensic exercise that risks altering metadata or breaching another person’s rights.

Potentially exculpatory material should be identified and preserved lawfully: full threads, original files, logs, backups, proof of shared use, legitimate records and device documentation. Preservation is not the same as sending everything to the police. Collection, review, privilege and deployment require separate advice.

16. Business, professional and third-party data

A seized device may contain client files, patient information, employee data, trade secrets, journalistic source material, privileged advice or safeguarding records. Criminal powers do not remove the practical consequences for innocent third parties. The response may require parallel advice on confidentiality, data protection, regulation and business continuity.

The immediate objective is a controlled solution: preserve the investigation while reducing unnecessary harm. Depending on the facts, that may mean priority imaging, a narrower protocol, independent privilege review, supervised access, specified copies, return of hardware after imaging or transfer of a telephone number. General demands are weaker than a precise proposal tied to operational need.

17. Retention and return

Property lawfully seized may be retained only for so long as necessary in all the circumstances for a permitted investigative, evidential or forensic purpose. Necessity can change. Once imaging or examination is complete, continued possession of the physical item may need fresh justification.

• Obtain or reconstruct an exact schedule of property and identifiers.
• Record the power and purpose asserted for each category.
• Explain any urgent personal, medical, professional or business impact with evidence.
• Ask whether a forensic copy, specified files or supervised access can meet the need.
• Seek a realistic examination timetable and named review date.
• Escalate to formal representations or an appropriate legal remedy where retention or scope can no longer be justified.

18. When objective material helps the defence

The strategic objective is not to prevent evidence being obtained. DNA may exclude the client. Location data may support an alibi. A full conversation may disprove a selected extract. Access logs may identify another user. Metadata may show that a file originated elsewhere. Photographs may record injuries consistent with self-defence.

Objective material is not owned by the prosecution or defence. The task is to ensure it is obtained lawfully, preserved reliably, interpreted in context and used to answer the correct proposition.

19. Immediate checklist

• Identify the exact act and legal power before advising on consent or refusal.
• Ask what proposition the step is intended to prove.
• Record authority, explanation, consent, objection, force, item identifiers and custody/search records.
• Raise vulnerability, dignity and healthcare issues before an intrusive procedure.
• Protect privilege through a specific segregation and review protocol.
• Separate device ownership, possession, control, account access and actual use.
• Give an express preservation warning; prohibit deletion, wiping and improvised self-help.
• Identify urgent access or business-continuity needs and propose a narrow solution.
• Set the next review point for examination, results, retention and return.

Legal source note

This chapter has been checked principally against the Police and Criminal Evidence Act 1984; PACE Codes B, C and D (2023); the Criminal Justice and Police Act 2001 seizure-and-sifting provisions; Part III of the Regulation of Investigatory Powers Act 2000; and Part 2, Chapter 3 of the Police, Crime, Sentencing and Courts Act 2022 with its statutory code on extraction of information from electronic devices. The guide states strategic principles, not an exhaustive account of every power or exception. The applicable version of legislation and Codes should be checked at the time of action.