IT Forensics · Courts

Is it possible to establish who has used a computer or a smartphone?

The question „Who used the device?“ is one of the most common – and at the same time most difficult – questions of evidence in IT forensics. A logged-in user account does not automatically prove that the person whose name is on the account was actually sitting at the device. The same applies to a smartphone that belongs to one person but may have been used by a third party.

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A reliable attribution cannot, therefore, be derived from a single artefact. It arises – if at all – from a chain of mutually compatible traces: login, device status, user profile, communication data, file activities, local or cloud-based accounts, biometric or device-specific indicators where applicable, and the temporal relationship with other events.

Our task is not to link a user account to a specific individual, but to explain to the court which links are technically verified, probable, merely possible or cannot be substantiated.

The actual question of evidence

What information might a user assignment contain?

Depending on the device and the issue at hand, log-in events, user accounts, session data, device associations, app accounts, communication logs, location or network references and file system activity may be relevant. Correlation is key.

An example: a Windows login at 10.02, a document opened at 10.05, and a message sent immediately afterwards from an account logged in under the same profile can, taken together, be more revealing than any single piece of evidence. Nevertheless, it is necessary to check whether automated processes, remote access or use by third parties might be considered as alternative explanations.

Where the limits of what can be said lie

Technical artefacts often initially identify an account, a session or a device – not necessarily the individual behind them. This distinction must remain clear in the report.

Why LanCologne?

In the case of court-ordered investigations, it is not a matter of which analysis programme displays a match first. What matters is whether the question of evidence can be answered on a technical basis and whether that answer stands up to independent scrutiny.

We adopt an open-minded approach, document the origin of key findings and examine alternative technical explanations. The actual analysis is always carried out on a forensic copy or a dataset that has been securely preserved as evidence. Originals are not examined directly unless absolutely necessary. Where live procedures are technically necessary, any changes that may result from them are explicitly documented.

Depending on the research question, key findings are verified either using a second method appropriate to the subject matter or directly on the basis of the underlying raw data. The tools used for this purpose depend on the evidence and the research question. The key factors are the suitability, professional recognition and traceability of the method – not a product name.

Our report distinguishes between factual findings, technical assessments and remaining uncertainties. A negative finding is justified just as carefully as a positive one.

How we handle court-ordered assignments

How we work – from the court order to the response

We first check whether the matter falls within our area of expertise, what facts the court is basing its decision on, and whether the content or scope of the assignment is clear. If there is any doubt, the court will seek clarification. This is in accordance with Sections 404a and 407a of the Code of Civil Procedure (ZPO).

Any reasons that might give rise to doubts as to impartiality are examined before the substantive investigation begins and, where appropriate, disclosed to the court.

Devices, data storage media, backups and files provided are identified and documented. The status at the time of the investigation is recorded.

Where technically feasible, a forensic copy or image is created. Hash values and other integrity checks are used to ensure unambiguous identification. The original is retained for future verification.

We determine which evidence would support the alleged event, what contradictory findings are conceivable, and which alternative technical explanations need to be examined.

Only those artefacts which have professional evidential value in relation to the issue in question are examined. Automatic matches are not accepted without verification.

Findings relevant to the decision are – where necessary – cross-checked using a second recognised method, a different technical approach or directly against the raw data.

We explicitly examine what conclusions must not be drawn from the data. We identify missing data, possible deletions, technical limitations, incomplete extracts or contradictory evidence.

The final conclusion is drawn from the documented findings. It is not stated in stronger terms than the data permit.

The main text remains accessible even to those without a background in digital forensics. The technical appendix contains the information required by an independent IT forensic expert to carry out a technical review or prepare a counter-report.

Sections 403, 404a, 407a and 411 of the Code of Civil Procedure (ZPO); Section 286 of the Code of Civil Procedure (ZPO) for the final judicial assessment. In criminal proceedings, Sections 72 et seq. of the Code of Criminal Procedure (StPO).

The expert provides the factual basis for the case. The legal assessment and the final evaluation of the evidence remain the responsibility of the court.

Frequently Asked Questions

LanCologne – IT Forensics for the Courts

Do you require an independent technical investigation into a matter of evidence for court proceedings? LanCologne examines digital evidence objectively, transparently and in a reproducible manner. We document both positive findings and the absence of evidence, as well as technical limitations, in such a way that the conclusions remain comprehensible to the court and verifiable by an independent IT forensic expert.

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