A digital forensics expert report (dictamen pericial) is the technical analysis of digital evidence (phones, computers, storage media, email accounts, WhatsApp chats or social media) carried out by an expert (perito) to answer specific questions in a case. Castro Defense provides this service to companies, law firms and individuals across Mexico, including foreign companies running internal investigations, whenever digital evidence has to hold up before a Mexican authority.
What can a forensic examination answer?
An expert report does not “find the truth” on its own. It answers precise questions with a method another expert can review and repeat. Typical questions include:
- Does this message or file exist, since when, and on which device?
- Was a conversation, email or document altered?
- Which account or device was involved in an event, and when?
- What can be recovered from a device, and with what limits?
These questions come up in criminal, labor, civil, family and administrative matters in Mexico, and in corporate investigations into fraud, data leaks or employee misconduct.
Case types Castro Defense handles: case types, e.g. fraud, WhatsApp and social media evidence, deleted data, email authenticity, workplace misconduct.
For employers: our time clock forensic certification helps your attendance records hold up in a Mexican labor dispute.
Why chain of custody matters for digital evidence
Mexico’s National Code of Criminal Procedure (Código Nacional de Procedimientos Penales, CNPP) defines chain of custody as the control and record-keeping system applied to evidence from the moment it is found or submitted until the competent authority closes it. It requires recording the item’s identity, original condition, how it was collected, preserved, packaged and moved, and the name of everyone who handled it (art. 227).
For digital evidence this means working on a forensic copy rather than the original, calculating hash values that prove the copy has not changed, and logging every access. Altered evidence does not lose its value automatically, but the authority may find that it can no longer prove the fact in question (art. 228).
Lawfulness matters too. Any evidence obtained in violation of fundamental rights is grounds for exclusion (CNPP, art. 264), so the analysis starts from devices and accounts that are legitimately accessible. Communications between private parties may be submitted when one of the participants obtained them directly (art. 276). For employers, that makes it important to confirm who owns a device or account before anyone examines it.
What to do in the meantime
- Do not delete, edit or forward the messages or files involved.
- Stop using the device where possible; do not reset it or send it for repair.
- Write down who has had the device and since when.
- Keep any screenshots you already have, but do not treat them as a substitute for the original.
How does the forensic process work?
- Initial consultation. We review the facts, the proceeding in which the report will be used and the questions it must answer. If a lawyer is already on the case, the scope is set with them.
- Preservation. A forensic image or the extraction suited to the device is made, hash values are calculated and the chain-of-custody record is opened.
- Analysis. The copy is examined with documented tools and procedures so another expert can verify the results.
- Report. The dictamen sets out the method, findings, limits and conclusions in language a Mexican court or prosecutor can follow.
- Explaining it to the authority. In criminal matters, a written report does not exempt the expert from testifying at trial (CNPP, art. 272). confirm whether expert testimony is included
Typical turnaround: typical turnaround for a report.
What is included?
- Case assessment and definition of the questions the report must answer.
- Evidence preservation and chain-of-custody documentation.
- Forensic analysis of devices, accounts or files.
- Written expert report.
- Coordination with your counsel or with Castro Defense’s legal defense team.
Confirmed deliverables: deliverables, e.g. written report, court testimony, chain-of-custody documentation.
Who can sign a forensic expert report in Mexico?
The CNPP requires experts to hold an official degree in the relevant field when that field is regulated. When it is not, the expert must be a person of evident competence, preferably a member of a professional association in the specialty (art. 369). Check any expert’s credentials before engaging them.
Credentials of Castro Defense’s expert: degrees, professional license (cédula profesional) and forensic certifications such as CHFI, EnCE, ACE or CCE, and any court registration as perito. Prosecutors’ offices or courts where the expert has acted: jurisdictions.
Forensics and legal defense, working together
A report is most useful when the legal strategy defines from the outset what needs to be proven. If your matter is already in a criminal investigation file (carpeta de investigación) or at trial, Castro Defense’s legal defense team can coordinate with the forensic work. This matters, for example, when an analysis will alter the evidence and cannot be repeated: the public prosecutor (Ministerio Público) must notify the defense so its expert can be present (CNPP, art. 274).
If the matter involves a drone, such as an unauthorized flight over a facility, you may also be interested in our counter-drone systems or drone pilot training.
This content is for information only and is not legal advice for a specific case. The outcome of any proceeding depends on the facts, the evidence and the authority’s decision; Castro Defense does not guarantee results.
Official sources
- National Code of Criminal Procedure (Código Nacional de Procedimientos Penales), arts. 227, 228, 264, 272, 274, 276 and 369. Chamber of Deputies, current text (Spanish).
Frequently asked questions
What is a digital forensics expert report in Mexico?
It is a written opinion (dictamen pericial) in which an expert (perito) analyzes digital evidence such as a phone, a computer, an email account or a chat, and documents the method, findings and conclusions. It can be offered as evidence in criminal, civil, labor or administrative proceedings, under the rules of each type of proceeding.
Is a WhatsApp screenshot valid evidence in Mexico?
It can be offered, but on its own it is easy to challenge because it does not show where it came from or whether it was altered. A forensic examination of the original device or conversation documents its origin, integrity and context. Mexico's National Code of Criminal Procedure allows private communications to be submitted when they were obtained directly by one of the participants (art. 276).
What does chain of custody mean for digital evidence?
It is the control and record-keeping system that documents who handled an item of evidence, when and under what conditions, from the moment it is found or submitted until the authority closes it (CNPP, art. 227). For digital evidence it also covers the forensic copies and their hash values, which show the data did not change.
Can deleted messages or files be recovered?
Sometimes. It depends on the device, its operating system, encryption, the time elapsed and how the device was used after deletion. No one can promise recovery before the analysis, so it is best to stop using the device and preserve it as soon as possible.
Can we hire our own expert if the prosecutor already has one?
Yes. Parties may offer their own expert evidence, and when an analysis cannot be repeated the code requires notice to the defense so its expert can attend or take part (CNPP, art. 274). A second report is also a way to test the method and conclusions of the official expert.