What do you use for 'Case number' in typical imaging tools?

[chrishargreaves]

As an example from an imaging tool:

Acquiry parameters required, please provide the necessary input
Image path and filename without extension: outfile
Case number: mycase1
Description: this is my case               
Evidence number: mycase/ev1
Examiner name: Examiner1
Notes: Some notes

Case number -> ???
Description -> https://ontology.unifiedcyberontology.org/uco/core/description
Evidence number -> https://ontology.caseontology.org/case/investigation/exhibitNumber
Examiner name -> https://ontology.unifiedcyberontology.org/uco/core/name
Notes -> https://ontology.unifiedcyberontology.org/uco/observable/Note

Case number could just be text, but it feels like something fundamental that should have a type? Am I missing something? uco-identity:IdentifierFacet maybe?

[vulnmaster]

We need a caseNumber property on the CASE Investigation class. We also need a mechanism to show relationships between investigations with different case numbers.

[chrishargreaves]

Ok in some ways I'm glad it's missing, not that I couldn't find it.

@prosch88 Not sure if you hit this too with your CASE/UCO output from ALEX/UFADE

[vulnmaster]

Change proposal written with the assistance of AI in response to the question opening this issue. The example graph and SPARQL queries below are CASE SHACL validated (see Pre-submission testing).

Target release

Target: CASE 1.5.0

Background

The question opening this issue — what does "Case number" from a typical imaging tool map to? — currently has no good answer, and the gap is deeper than one property:

1. No case number property. investigation:Investigation has investigationForm, investigationStatus, and focus, but no identifier property. Adjacent terms don't fit: investigation:exhibitNumber identifies evidence items, not cases; uco-core:name is a display name, not an identifier; uco-identity:IdentifierFacet is scoped to identities ("uniquely and specifically identifies an entity" within identity:Identity); uco-core:externalIdentifier has the right semantics ("an identifier for some information defined external to the UCO context") but is generic, undiscoverable, and not associated with Investigation in any shape or documentation — which is why tool authors end up asking this question.

2. No mechanism for relating investigations that carry different case numbers. Real matters routinely span organizations, each of which opens its own case. A concrete ICAC example:

   • A technology platform's trust & safety team opens internal case TS-2026-88041,
   • files a NCMEC CyberTipline report, which receives report ID CT-2026-1234567,
   • NCMEC routes it to a state ICAC task force, which opens case ICAC-AK-2026-0113,
   • the task force refers it to a local police department, which opens case 2026-004567,
   • local police seize an encrypted smartphone and submit it to the state crime laboratory, which opens lab case SCDL-26-0892.

   Five organizations, five case numbers, one investigative continuum. Today CASE cannot express that these cases are related, in what way, or in what direction — so a graph assembled from all five organizations' records (exactly the cross-tool interchange CASE exists for) cannot be traversed from CyberTip to lab report.

The same pattern appears far beyond ICAC: incident response cases escalating to regulator cases, corporate internal investigations referred to law enforcement, task-force cases spawning per-defendant prosecutions, lab submissions, and mutual legal assistance requests between jurisdictions.

What we achieve for whom and why it matters: Tool authors get a direct, documented answer for the ubiquitous "Case number" field; investigators and analysts get a standard way to stitch multi-agency case chains into one traversable graph; and application-domain ontologies (CAC Ontology and others) inherit both concepts from CASE instead of minting their own — the CAC Ontology has already had to propose a local cacontology:caseNumber (CAC-Ontology #41) precisely because CASE offers no term to inherit.

Relationship to other proposals: This complements the three legal process and procedure namespace proposals (#192 criminal, #193 civil, #194 corporate): case numbers identify matters in all three arenas (police case numbers, court dockets, corporate matter numbers), and a #194 Referral handing a corporate matter to law enforcement is exactly the event that produces a related investigation with a new case number. It is orthogonal to #138 (Investigation as Event specialization) and to #189 (process meta-model), both of which would benefit from — but do not conflict with — these terms. UCO #554 (work ticket concept) covers the analogous ticket-number pattern for help-desk workflows and could align with the same externalIdentifier grounding.

Requirements

Requirement 1 — investigation:caseIdentifier

Add a datatype property to the investigation: namespace:

• Name: caseIdentifier (suggested; caseNumber is the colloquial term but many systems issue non-numeric identifiers)
• rdfs:subPropertyOf uco-core:externalIdentifier — inheriting UCO's identifier semantics: the value is assigned by a case-management authority external to the graph
• Domain: investigation:Investigation (via SHACL property shape on the Investigation shape; multiple values permitted, since one organization may assign several identifiers to one case)
• Range: xsd:string

This directly answers the mapping table in the opening comment:

Imaging tool field	CASE/UCO term
Case number	investigation:caseIdentifier (proposed) on the investigation:Investigation node
Description	uco-core:description
Evidence number	investigation:exhibitNumber
Examiner name	uco-core:name on the investigation:Examiner role / identity
Notes	uco-observable:Note

Requirement 2 — Related-investigation representation

Standardize how investigations with different case identifiers are related, using the existing uco-core:Relationship machinery rather than new object properties:

• Document (and optionally subclass) the pattern: a uco-core:Relationship whose source and target are investigation:Investigation nodes.
• Recommend an open vocabulary for uco-core:kindOfRelationship between investigations, e.g.: Referred_To (matter handed to another organization), Escalated_To, Spawned (parent case opens child case, e.g. per-defendant prosecutions), Merged_Into, Parallel_To (concurrent related cases), Evidence_Submitted_To (lab submission), Successor_Of.
• Optionally, add investigation:InvestigationRelationship rdfs:subClassOf uco-core:Relationship with SHACL constraining source/target to investigation:Investigation, so tools can find inter-case links without inspecting every Relationship. The committee may prefer the documentation-only variant; either resolves the gap. The example below uses the typed subclass.

Requirement 3 — Non-prescriptive and inheritable

Both terms carry no workflow or jurisdictional commitments. Application-domain ontologies specialize them, e.g. cacontology:caseNumber rdfs:subPropertyOf investigation:caseIdentifier (re-parenting the CAC-Ontology #41 proposal), or a lab-domain ontology declaring lab:SubmissionRelationship rdfs:subClassOf investigation:InvestigationRelationship.

Risk / Benefit analysis

Benefits

1. Answers a real, recurring tool-mapping question — the imaging-tool field prompting this issue is present in essentially every acquisition and case-management tool (FTK Imager, Cellebrite, Magnet AXIOM, lab LIMS).
2. Multi-agency traversal — one SPARQL query walks the CyberTip-to-lab chain across five organizations' graphs.
3. Grounded in existing UCO semantics — caseIdentifier refines uco-core:externalIdentifier; relating investigations reuses uco-core:Relationship. Minimal new surface area.
4. Stops downstream forking — CAC-Ontology Ont 251 #41 already had to propose caseNumber locally for want of a CASE parent; other domain ontologies will follow.
5. Composes with the 1.5.0 agenda — investigator roles (Addition of Investigator Subclasses #178/Issue 178 addition of CASE investigation:Investigator subclasses #183/Add Analyst Role to CASE #187), legal process namespaces (Add Criminal Process and Procedure Namespace (Stub Concepts) #192–Add Corporate Process and Procedure Namespace (Stub Concepts) #194), and the Adopting CASE Investigation Ontology by Communities with Defined Business Rules #189 process meta-model all produce or consume case identifiers and inter-case links.

Risks

• Naming: caseIdentifier vs caseNumber. Mitigation: committee choice; a skos:altLabel "case number" preserves findability either way.
• Property proliferation on Investigation: one property, subproperty of an existing core term — minimal.
• Vocabulary drift in kindOfRelationship values between investigations. Mitigation: publish the recommended values as a semi-open vocabulary (the same approach as InvestigationFormVocab), leaving room for domain values.
• Overlap concern with uco-identity:IdentifierFacet: that facet identifies identities; a case identifier identifies a compilation of investigative context. Documentation should state the distinction (it is the very confusion the opening comment raises).
• The submitter is unaware of other risks.

Competencies demonstrated

Competency 1

Scenario: The five-organization ICAC chain above: platform trust & safety case TS-2026-88041 → NCMEC CyberTip CT-2026-1234567 → state ICAC task force case ICAC-AK-2026-0113 → local police case 2026-004567 → state lab case SCDL-26-0892 (encrypted phone submission).

Competency Question 1.1

Given the local police case number 2026-004567, what related cases exist across all organizations, with what case identifiers, and how are they related?

Result 1.1

Case	Identifier	Relation to chain
Platform T&S internal investigation	TS-2026-88041	Referred_To NCMEC CyberTip intake
NCMEC CyberTipline report handling	CT-2026-1234567	Referred_To state ICAC task force case
State ICAC task force case	ICAC-AK-2026-0113	Referred_To local police case
Local police case	2026-004567	Evidence_Submitted_To state lab case
State lab examination case	SCDL-26-0892	(terminal node)

Competency Question 1.2

Which investigations in the graph carry which case identifiers (the imaging-tool "Case number" lookup)?

Result 1.2

All five investigations return their caseIdentifier values in one query, regardless of which organization's tooling produced each subgraph.

Draft SPARQL

PREFIX investigation: <https://ontology.caseontology.org/case/investigation/>
PREFIX uco-core: <https://ontology.unifiedcyberontology.org/uco/core/>
PREFIX proposed: <http://example.org/ontology/proposed/investigation/>

SELECT ?sourceCase ?kind ?targetCase
WHERE {
    ?rel a proposed:InvestigationRelationship ;
         uco-core:source ?src ;
         uco-core:target ?tgt ;
         uco-core:kindOfRelationship ?kind .
    ?src proposed:caseIdentifier ?sourceCase .
    ?tgt proposed:caseIdentifier ?targetCase .
}

# ---

PREFIX investigation: <https://ontology.caseontology.org/case/investigation/>
PREFIX uco-core: <https://ontology.unifiedcyberontology.org/uco/core/>
PREFIX proposed: <http://example.org/ontology/proposed/investigation/>

SELECT ?investigationName ?caseId
WHERE {
    ?inv a investigation:Investigation ;
         uco-core:name ?investigationName ;
         proposed:caseIdentifier ?caseId .
}

Example instance data

The example graph is available as a standalone file (change_proposals/case-number-and-related-investigation-representation.jsonld) for validation and SPARQL testing. Proposed terms use a proposed: placeholder namespace pending committee decisions. I am fine with my examples being transcribed and credited.

{
  "@context": {
    "kb": "http://example.org/kb/",
    "proposed": "http://example.org/ontology/proposed/investigation/",
    "case-investigation": "https://ontology.caseontology.org/case/investigation/",
    "uco-core": "https://ontology.unifiedcyberontology.org/uco/core/",
    "xsd": "http://www.w3.org/2001/XMLSchema#"
  },
  "@graph": [
    {
      "@id": "kb:investigation-platform-ts",
      "@type": "case-investigation:Investigation",
      "uco-core:name": "Platform trust & safety internal investigation",
      "proposed:caseIdentifier": "TS-2026-88041"
    },
    {
      "@id": "kb:investigation-ncmec-cybertip",
      "@type": "case-investigation:Investigation",
      "uco-core:name": "NCMEC CyberTipline report handling",
      "proposed:caseIdentifier": "CT-2026-1234567"
    },
    {
      "@id": "kb:investigation-state-icac",
      "@type": "case-investigation:Investigation",
      "uco-core:name": "State ICAC task force case",
      "proposed:caseIdentifier": "ICAC-AK-2026-0113"
    },
    {
      "@id": "kb:investigation-local-pd",
      "@type": "case-investigation:Investigation",
      "uco-core:name": "Local police department case",
      "proposed:caseIdentifier": "2026-004567"
    },
    {
      "@id": "kb:investigation-state-lab",
      "@type": "case-investigation:Investigation",
      "uco-core:name": "State crime laboratory examination (encrypted smartphone)",
      "proposed:caseIdentifier": "SCDL-26-0892"
    },
    {
      "@id": "kb:rel-ts-to-ncmec",
      "@type": "proposed:InvestigationRelationship",
      "uco-core:source": { "@id": "kb:investigation-platform-ts" },
      "uco-core:target": { "@id": "kb:investigation-ncmec-cybertip" },
      "uco-core:kindOfRelationship": "Referred_To",
      "uco-core:isDirectional": true
    },
    {
      "@id": "kb:rel-ncmec-to-icac",
      "@type": "proposed:InvestigationRelationship",
      "uco-core:source": { "@id": "kb:investigation-ncmec-cybertip" },
      "uco-core:target": { "@id": "kb:investigation-state-icac" },
      "uco-core:kindOfRelationship": "Referred_To",
      "uco-core:isDirectional": true
    },
    {
      "@id": "kb:rel-icac-to-local",
      "@type": "proposed:InvestigationRelationship",
      "uco-core:source": { "@id": "kb:investigation-state-icac" },
      "uco-core:target": { "@id": "kb:investigation-local-pd" },
      "uco-core:kindOfRelationship": "Referred_To",
      "uco-core:isDirectional": true
    },
    {
      "@id": "kb:rel-local-to-lab",
      "@type": "proposed:InvestigationRelationship",
      "uco-core:source": { "@id": "kb:investigation-local-pd" },
      "uco-core:target": { "@id": "kb:investigation-state-lab" },
      "uco-core:kindOfRelationship": "Evidence_Submitted_To",
      "uco-core:isDirectional": true
    }
  ]
}

Solution suggestion

@prefix investigation: <https://ontology.caseontology.org/case/investigation/> .
@prefix uco-core: <https://ontology.unifiedcyberontology.org/uco/core/> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

investigation:caseIdentifier
    a owl:DatatypeProperty ;
    rdfs:subPropertyOf uco-core:externalIdentifier ;
    rdfs:label "caseIdentifier"@en ;
    skos:altLabel "case number"@en ;
    rdfs:comment "An identifier assigned to an investigation by the organization or case-management authority conducting or tracking it, e.g. a police case number, CyberTipline report ID, laboratory submission number, or court docket number. An investigation may carry multiple case identifiers. Distinct organizations investigating related matters each assign their own case identifiers; relate such investigations with an InvestigationRelationship."@en ;
    rdfs:range xsd:string .

investigation:InvestigationRelationship
    a owl:Class ;
    rdfs:subClassOf uco-core:Relationship ;
    rdfs:label "InvestigationRelationship"@en ;
    rdfs:comment "An investigation relationship is a grouping of characteristics unique to an assertion of an association between two investigations, typically conducted by different organizations under different case identifiers. Recommended kindOfRelationship values (open vocabulary): 'Referred_To', 'Escalated_To', 'Spawned', 'Merged_Into', 'Parallel_To', 'Evidence_Submitted_To', 'Successor_Of'."@en .

Plus a SHACL property shape adding caseIdentifier to the investigation:Investigation node shape, and sh:class investigation:Investigation constraints on uco-core:source/uco-core:target of InvestigationRelationship. If the committee prefers not to add the subclass, Requirement 2 can be met with documentation of the plain uco-core:Relationship pattern; caseIdentifier (Requirement 1) stands alone either way.

Related proposals and references

Reference	Relevance
This issue (CASE #191)	The tool-mapping gap this proposal fills.
CAC-Ontology #41	CAC had to propose a local caseNumber (as rdfs:subPropertyOf uco-core:externalIdentifier) for want of a CASE parent; it would re-parent to investigation:caseIdentifier.
CASE #192 / #193 / #194 — legal process namespace stubs	Criminal dockets, civil actions, and corporate matters all carry case identifiers; a #194 Referral produces a related investigation with a new case number.
CASE #189 — process meta-model	Workflow runs and gates operate within cases identified and chained by these terms.
CASE #178 / #183 / #187 — roles	Different investigator roles sit at different links of the case chain (T&S analyst, LE investigator, lab examiner).
CASE #138 — Investigation as Event	Orthogonal; no conflict with either superclass decision.
UCO #554 — Work ticket concept	The analogous ticket-number pattern; both ground in uco-core:externalIdentifier.
NCMEC CyberTipline	Real-world referral pipeline motivating the multi-organization scenario.

Pre-submission testing

SPARQL query testing

Query	Tested	Expected results match	Notes
CQ 1.1 — case chain with identifiers and relation kinds	Yes	Yes	4 results: TS→CyberTip→ICAC→local PD (Referred_To ×3), local PD→lab (Evidence_Submitted_To)
CQ 1.2 — caseIdentifier lookup per investigation	Yes	Yes	5 results, one per organization

Graph validation

$ make test-proposal PROPOSAL=case-number-and-related-investigation-representation
case_validate --built-version case-1.4.0 --inference rdfs --allow-info \
  --ontology-graph change_proposals/case-number-and-related-investigation-representation.ttl \
  change_proposals/case-number-and-related-investigation-representation.jsonld
Validation Report
Conforms: True

Unresolved issues

• caseIdentifier vs caseNumber naming, and typed-subclass vs documentation-only for Requirement 2, are committee decisions; the example uses a proposed: placeholder namespace.
• Whether the recommended inter-investigation kindOfRelationship values should become a formal semi-open vocabulary (like InvestigationFormVocab) is left to committee preference.
• Human-readable IRIs are used in the example for readability; production data should use UUID-based IRIs.

[chrishargreaves]

For into it came up developing this technique for reading embedded metadata within forensic containers. Most mapped sensibly but with an obvious omission in case number.

SOLVE-IT-DF/solve-it#504

"CASE_output_classes": [
"https://ontology.caseontology.org/case/investigation/exhibitNumber",
"https://ontology.unifiedcyberontology.org/uco/core/name",
"https://ontology.unifiedcyberontology.org/uco/observable/Note",
"https://ontology.unifiedcyberontology.org/uco/core/description",
"https://ontology.unifiedcyberontology.org/uco/types/Hash"
],

[prosch88]

Ok in some ways I'm glad it's missing, not that I couldn't find it.

@prosch88 Not sure if you hit this too with your CASE/UCO output from ALEX/UFADE

ALEX and UFADE do not currently assign a case number for the CASE output, since assigning a case number during Backup is currently optional.

[chrishargreaves]

Ok in some ways I'm glad it's missing, not that I couldn't find it.
@prosch88 Not sure if you hit this too with your CASE/UCO output from ALEX/UFADE

ALEX and UFADE do not currently assign a case number for the CASE output, since assigning a case number during Backup is currently optional.

Ah ok thanks. But if we get this in, if it that field was completed during export then it could go in this property. It's very helpful to have real examples of where it would be used.

[eoghanscasey]

CASE Investigation currently uses "uco-core:name" for this type of case/investigation identifier.

See examples on website:

https://caseontology.org/examples/asgard/
https://caseontology.org/examples/crossover/
https://caseontology.org/examples/owl_trafficking/

   {
        "@id": "kb:bundle-5715fcf3-6bc8-4996-8f7f-fdf289f31649",
        "@type": "uco-core:Bundle",
        "uco-core:description": "Evidence in illegal trafficking of owls",
        "uco-core:object": [
            {
                "@id": "kb:investigation-555e5fbb-ba09-449d-af77-8a210d016fd7",
                "@type": "case-investigation:Investigation",
                "uco-core:name": "OWL_2017_0206001",
                "case-investigation:focus": "Illegal trafficking (owls)",
                "uco-core:description": "The subject mcavoy was arrested on suspicion of illegal trafficking of owls. His computer and smartphone were preserved as evidence.",
                "rdfs:comment": "TODO - uco-core:object to list more IRIs.",
                "uco-core:object": [
                    {
                        "@id": "kb:lge-device-eee670c6-01d4-4e42-bb6b-ebeca149b168"
                    }
                ]
            }
        ]
    },

Also shown in some illustrative CASE-Examples:

https://github.com/casework/CASE-Examples/blob/master/examples/illustrations/Oresteia/Oresteia.json

[vulnmaster]

@eoghanscasey uco-core:name is just a subjective label. You could name the investigation "dog", "vehicle-investigation", or any other random string. We need a dedicated caseNumber property that is defined for this purpose.

[eoghanscasey]

That shouldn't be hard, just need to clearly document the change so that past CASE data can be migrated from "uco-core:name" to caseNumber (or caseIdentifier?).

[chrishargreaves]

Preference for something like caseIdentifier if this progresses since they aren't always numbers.

[joachimmetz]

As an example from an imaging tool:

That output looks familiar :D

For context the imaging tool here, matches common metadata based on reference implementation(s).

I would also indicate "evidence" in the context of related tooling/format, IMHO is not the appropriate nomenclature, but again aligns with the reference implementation(s) (at least at the time).

How I used "case number" previously, is mostly as a reference, e.g. a tracking ticket/case/investigation number/reference/identifier. Definitely not bound to a numeric only value

Also note that in the context of specifically DFIR, terminology like "investigation" might refer mostly to insider threat related cases versus intrusions. Where a case might be used as synonym that includes a (tracking) tickets for intrusion alerts and/or a (legal/ediscovery) matters

[plbt5]

An investigation:caseIdentifier is defined as "An identifier assigned to an investigation". With such definition, clearly we should speak about investigation:investigationIdentifier. Vice versa, when reasons exist to maintain the property name investigation:caseIdentifier, then clearly the definition should read "An identifier assigned to a case".