January 16, 2026 | Operational Policing, Investigations and Events , Forensics
Request Number: FOI/16329
Category: Operational policing, Investigations and Events - Forensics
Subject: AI-assisted evidence analysis
Request and Answer:
Your request for information below has now been considered. In respect of Section 1(1)(a) of the Freedom of Information Act 2000 (FOIA) and we can neither confirm nor deny that the Police Service of Northern Ireland does or does not hold the information you have requested. It is estimated that the cost of complying with your request for information would exceed the “appropriate costs limit” under Section 12(2) of the Freedom of Information Act 2000.
Request
I am investigating how AI-assisted evidence analysis is documented and reported within existing Chain of Custody (CoC) and Audit Trail (AT) structures.
For the sake of clarity, I have included a glossary at the end of this document. CoC is used here as an umbrella term encompassing related concepts such as continuity, chain of evidence, and provenance; while AT refers to any documentation system that captures and records the forensic processing of evidence.
Request 1
Does your police force deploy Artificial Intelligence (AI) systems in areas including investigation, intelligence, operations, case management, or evidence processing? If yes, please provide:
a) The names of the tools, underlying technology, software versions, and primary use cases.
b) Whether each tool is internally developed or procured from third-party providers.
c) The name of the providers and a copy of any related contract documents.
d) The current status of each tool (in trial/pilot stage, under evaluation, or fully deployed).
e) Whether each AI tool is embedded in any forensic platform(s), or whether it operates as a separate, standalone system for specific tasks.
Request 2
Does your police force use Natural Language Processing (NLP), including Large Language Models (LLMs), Automatic Speech Recognition (ASR), or other AI technologies for processing and analysing forensic audio and textual evidence, (covering tasks including transcription, speaker diarisation, translation, summarisation, redaction, document generation, or form-filling)? If yes, please provide:
a)The names of the tools, underlying technology, software versions, and primary use cases.
b) Whether each tool is internally developed or procured from third-party providers.
c) The name of the providers and a copy of any related contract documents.
d) The current status of each tool (in trial/pilot stage, under evaluation, or fully deployed).
e) Whether each AI tool is embedded in any forensic platform(s), or whether it operates as a separate, standalone system for specific tasks.
Request 3
Does your force have any specific policies, or protocols governing the use of AI tools in processing and analysing forensic audio and textual evidence, or other forms of evidence? Please attach or reference any documents related to this.
Request 4
Is the chain of custody (CoC) and/or audit trail (AT) recorded when digital evidence, broadly speaking, are processed and analysed? If yes, please provide:
a) Details of the information that is recorded (e.g., evidence identifiers, date/time of transfers, personnel identifiers, storage/access logs, integrity checks).
b) Details of any technical or procedural methods used to record or track the CoC and/or AT. Kindly specify if the process is automated, manual, or hybrid.
c) Please indicate whether any verification or validation procedures are in place to confirm that digital evidence, upon acquisition, is a genuine and unmodified record rather than a synthetically generated or manipulated.
d) Any guidelines, practice directions, or policies guiding the documentation of CoC and/or AT for digital evidence, including any templates or forms. Kindly attach or reference related documents.
e) Has your force conducted any internal evaluations or comparisons regarding the efficiency, accuracy or reliability of automated, manual, or hybrid reporting methods? If yes, please provide copies or references.
f) Is the maintenance of a CoC and/or AT managed in-house or outsourced?
g) If in-house, provide details of the responsible role(s) or department(s), including any training materials or internal guidance relevant to this task.
h) If outsourced, please provide the name of the provider(s), a description of their role, and any related contract document(s).
Request 5
Is the chain of custody (CoC) and/or audit trail (AT) recorded when AI systems are used in processing and analysing forensic audio and textual data, or other forms of evidence? If yes, please provide:
a) Details of the information that is recorded, which may include but is not limited to identifier of the evidence, details of the AI model (e.g., version, provider), verified error rates, and identification of human oversight (if applicable).
b) Please indicate whether any paradata is captured during the processing of digital evidence. By paradata, I refer to information generated as a by-product of human interaction with the AI systems during evidence processing (e.g. prompts, edit history, data discards, interaction logs, correction logs, reviewer annotations, parameter adjustments, iterations).
c) Details of any technical or procedural methods used to document CoC and/or AT of AI-assisted evidence analysis, including any templates or forms. Kindly specify if the process is automated, manual, or hybrid.
d) Has your force conducted any internal evaluations or comparisons regarding the efficiency, accuracy, or reliability of automated, manual, or hybrid reporting methods? If yes, please provide copies or references.
e) Any guidelines or practice directions guiding the documentation of CoC and/or AT specific to AI-assisted evidence analysis. Kindly attach or reference related documents.
f) Is the maintenance of a CoC and/or AT managed in-house or outsourced?
g) If in-house, provide details of the responsible role(s) or department(s), including any training materials or internal guidance relevant to this task.
h) If outsourced, please provide the name of the provider(s), a description of their role, and any related contract document(s).
Request 6
Are human reviewers involved in reviewing, correcting, or contributing to the outputs generated by the AI systems in processing and analysing forensic audio and textual evidence? If yes:
a) What is the formal description of the role(s), and what specific responsibilities do individuals in these roles carry out?
b) What training materials or internal guidance are provided to support these roles?
c) How is human contribution tracked and distinguished?
d) Are records maintained for the different versions of outputs produced during the human-AI collaborative process?
Request 7
How is evidential disclosure managed in criminal proceedings where AI systems are used in processing and analysing forensic audio, textual data, or other forms of evidence?
a) Please specify the nature of materials disclosed to defence teams (e.g. final transcript only or detailed version history; original audio; AI model metadata etc?
b) Are the documentations of CoC and/or AT disclosed to the defence team? If yes, in what format is this made available?
c) Is there a standard procedure or checklist governing this? If so, please provide a copy or reference it.
Request 8
Has your force conducted any evaluations or assessments regarding the effectiveness of AI systems for evidence processing, including audio, textual, or other forms of evidence? If yes, please provide copies of these documents or reports.
Clarification Requested
1. Could you advise which business areas of policing your requests refer to? For example, is it AI systems within digital forensics or operational policing or any area?
2. For request 4, can you explain what you mean by digital evidence? For example, emails, CCTV, Bodycam footage or seized devices etc.
2a. Request 4 speaks of two concepts combined: CoC and AT which are related but distinct. Do you require separate answers for CoC and AT?
2b. Could you also clarify
at what stage of the process do you seek this information? The lifecycle of digital evidence is that it is collected/seized, retained, analysed, stored, and may later be disclosed at Court.
2c. Could you provide a time frame within which we are to search for this information?
3. For request 5, could you specify the evidence types you are seeking information on (such
as body worn video transcription, or interview summaries)?
3a. Could you also provide a timeframe for the data you seek?
4. For request 8, could you provide a timeframe for the information you seek?
Clarification Received
Business area of policing
The requests relate primarily to the digital forensics department and investigation unit, or the equivalent within the force.
Type of Evidence (Request 4 and 5)
The request focus is on audio and textual digital evidence processed for legal or investigative purposes:
- Audio evidence: Recorded sound collected, preserved, and analysed for evidential use. Examples include investigative interviews, emergency call recordings, body-worn camera audio, and dashcam recordings.
- Textual evidence: Written or encoded content collected, preserved, and analysed for evidential use. Examples include: interview transcripts, statements, emails, chat logs, and social media content. These examples are illustrative rather than exhaustive.
While the primary focus is on audio and textual evidence, "digital evidence, broadly speaking” may also include visual evidence (e.g., CCTV, body-worn video, photographs) if possible, to provide context for chain of custody and audit trail practices.
Chain of Custody and Audit Trail
Separate information is requested for Chain of Custody (CoC) and Audit Trails (AT), recognising that they are related but distinct concepts.
Stage of evidence lifecycle
The focus is the analysis stage. Information relating to other lifecycle stages is welcome if possible.
Timeframe for Request 4 and 5
I am only interested in the current procedure, so in terms of a definitive timeframe, 1st January 2025 till the date of the request.
Answer
Section 17(5) of the Freedom of Information Act 2000 requires the Police Service of Northern Ireland (PSNI), when refusing to provide such information (because the cost of compliance exceeds the appropriate limit) to provide you the applicant with a notice which states that fact.
It is estimated that the cost of complying with your request for information would exceed the “appropriate costs limit” under Section 12(2) of the Freedom of Information Act 2000. Section 12 of FOIA allows a public authority to refuse to deal with a request where it estimates that it would exceed the appropriate limit to either comply with the request in its entirety or confirm or deny whether the requested information is held. The estimate must be reasonable in the circumstances of the case. The ‘appropriate limit’ is currently £600 for central government and £450 for all other public authorities including PSNI. The relevant Regulations which define the appropriate limit for section 12 purposes are The Freedom of Information and Data Protection (Appropriate Limit and Fees) Regulation 2004 SI 2004 No 3244. These are known as the ‘Fees Regulations’ for brevity.
Regulation 4(3) of the Fees Regulations states that a public authority can take into account the costs it reasonably expects to incur in carrying out the following permitted activities in complying with the request:
(i) determining whether the information is held;
(ii) locating the information, or a document containing it;
(iii) retrieving the information, or a document containing it; and
(iv) extracting the information from a document containing it.
Under those regulations PSNI can calculate the time spent on each of these permitted activities at £25 per hour (thus if the activity(s) takes more than 18 hours PSNI will be in excess of the ‘appropriate limit’).
When a public authority is estimating whether the appropriate limit is likely to be exceeded, it can include the costs of complying with two or more requests if the conditions laid out in Regulation 5 of the Fees Regulations can be satisfied. Those conditions require the requests to be: made by one person, or by different persons who appear to the public authority to be acting in concert or in pursuance of a campaign; made for the same or similar information; and received by the public authority within any period of 60 consecutive working days.
Under Section 12 of the Freedom of Information Act 2000, if a public authority estimates that it would exceed the appropriate limit to confirm whether or not the requested information is held, under Section 12(2) of the Act, it does not have to deal with the substance of the request.
Regulation 5(2) of the Fees Regulations requires that the requests which are to be aggregated relate “to any extent” to the same or similar information. This is quite a wide test but public authorities should still ensure that the requests meet this requirement.
Enquiries made in relation to Requests 5, 6 and 7 have identified that even to establish if we hold the requested information, would require a manual trawl of all of PSNI’s case records as well as all departments that may or may not have been involved in each individual case. This would therefore exceed the FOI legislative cost of 18 hours as set by the Secretary of State.
The requested information outlined above, if held, would not be held centrally. In order to establish whether or not the information is held in all aspects, would require a manual review of all case records and electronic systems as well as every department involved in each individual case. This may also include contacting all officers from all departments in order to ascertain if there is any relevant recorded information. It is estimated that this process would grossly exceed the 18 hour cost limit.
In accordance with the Freedom of Information Act 2000, this letter should be considered as a Refusal Notice, and the request has therefore been closed.
Advice and assistance
You may wish to submit a refined request in order that the cost of complying with your request may be facilitated within the ‘appropriate limit’. In compliance with Section 16 of the Act, we have considered how your request may be refined to bring it under the appropriate limit.
Requests 1, 2, 3, 4, 8 - A response can be provided, but will likely be subject to exemptions.
Requests 5, 6 and 7 - Unfortunately, due to the extensive amount of searches that would be required to determine if the information is held, there is no refinement that would bring these requests within cost.
Submission of a refined request would be treated as a new request, and considered in accordance with the Freedom of Information Act 2000, including consideration of relevant Part II exemptions.