How Is Digital Evidence Preserved in Modern Investigations?

By Dr. Matthew Loux and Bryce Loux  |  09/11/2025

Digital evidence is increasingly important in today’s legal processes. As technology advances, so does law enforcement’s reliance on digital evidence.

Digital evidence helps in solving computer crimes, corporate digital investigations, and fraud cases. Evidence can be gathered from:

• Emails
• Word documents
• Mobile devices
• Text messages
• Network traffic
• Spreadsheets
• Cloud servers
• Photos
• Log files
• Metadata records
• Social media sites

Compared to physical evidence, digital evidence is much more fragile. Unlike investigation tools used to capture tangible physical evidence, digital evidence and its digital footprint can be easily altered, deleted, or corrupted.

Any attempts to modify evidence, whether done on purpose or not, can make that evidence null and void in a courtroom. As a result, safeguarding against any alteration is required to retain legal validity.

It is vital to understand the practice of maintaining digital evidence integrity from the moment of its collection to the final step of presenting it in the legal courtroom. To ensure the validity of findings, digital evidence requires:

• Specialized tools and techniques
• Cooperation among investigators, lawyers, and digital forensic consultants

What Is Digital Evidence?

Digital evidence is any information stored or communicated in a digital format that can be used in a legal investigation or trial. This information may be stored on physical devices (such as a thumb drive, laptop, or mobile phone) or an online site hosted by a cloud server.

Collecting digital evidence can be difficult due to its fragile nature. Additionally, digital evidence is often encrypted, password-protected, or kept in hidden places such as temporary files. Because digital evidence is so difficult to retrieve or preserve, it requires specialized tools, knowledge, and expertise.

To be used in a court of law, digital evidence must meet the same requirements as physical evidence. Investigators must demonstrate authenticity, reliability, and a verified chain of custody. Investigators must also show that the evidence was legally collected and has not changed since it was gathered.

Why Evidence Integrity Matters to Modern Investigations

Preventing the tampering, corruption, or loss of digital evidence makes preservation techniques necessary. In legal matters, even the smallest change can alter an investigation or cause essential data to be omitted from judicial proceedings.

Digital evidence preservation is threatened by numerous factors, including:

• User error
• Accidental or purposeful deletion by a user
• Failing hardware
• Power interruptions
• Malware
• Computer viruses
• System updates

The social and legal consequences of improperly collecting digital evidence are very serious. In some instances, not preserving evidence has led to cases being dismissed or charges reduced for a perpetrator.

As soon as digital evidence is located, law enforcement agencies, forensic investigators, and legal teams must institute preservation measures. Preservation can be achieved by formulating policies to:

• Validate tools and procedural practices
• Keep meticulous records
• Upholding evidence integrity

Core Principles of Digital Evidence Preservation

Digital evidence is multi-faceted. It depends on several core principles:

• Forensic soundness – All methods of preservation must be reliable, repeatable, and accepted in the forensic community.
• Chain of custody – Each person who handles the evidence must be recorded and documented. This work includes recording the time and the purpose for digital evidence collection.
• Evidence of integrity – Hash algorithms may be used to create unique fingerprints of digital files. These algorithms verify that electronic evidence has not been altered at any stage of the collection process.
• Minimal handling – Because even a small change can compromise original electronic evidence, investigators should analyze copies made from write blockers and not the original.

A strong focus on these principles helps investigators preserve authenticity and legal validity throughout the process.

The Components of Electronic Evidence Preservation

Preserving electronic evidence involves different components. These components are involved in safeguarding the information stored in digital devices and other storage areas:

• Imaging tools – Tools such as FTK Imager® and EnCase® create forensic images of hard drives and storage devices. Original data captured from the devices includes hidden and deleted data or files.
• Hash algorithms – To ensure the integrity of digital evidence, MD5, SHA-1, and SHA-256 algorithms can be used to create hash values. Such hashes can be generated at collection and throughout the process to verify that evidence hasn’t been altered.
• Write blockers – Data modification can be prevented during forensic investigations using write blockers. Without write blockers, data can be changed either on purpose or accidentally during access.
• Cloud forensics – Cloud storage of data requires forensic teams to employ application programming interfaces (APIs) and other secure tools to retrieve user data and metadata. To capture and store cloud evidence, tools like Magnet Forensics’ Axiom® and X1 Social Discovery® can be used.
• Mobile device acquisition – With software tools from companies such as Cellebrite UFED and Oxygen Forensics, it is possible to extract call logs, messages, application data, and deleted files from smartphones and tablets without compromising evidence integrity.

Stages of Preserving Digital Evidence

Safeguarding digital evidence requires great care and precision at every stage:

• Identification – Investigators look for devices that are likely to hold digital evidence. These sources include computers, mobile phones, cloud servers, and other electronic devices at or beyond the crime scene.
• Collection – After evidence sources have been identified, the next step is to gather the data without changing the original files. Investigators commonly use trusted tools, including write blockers.
• Preservation – The collected evidence is stored in secure facilities or cold storage. These are read-only environments that block unauthorized access and data decay.
• Documentation – Detailed logs are maintained to uphold the chain of custody, ensure legal admissibility, and show a clear record of how critical data was preserved.
• Analysis – All investigative tasks are conducted on replicas of the original pieces of evidence. Utilizing forensic tools, analysts assist in locating pieces of pertinent information while the original information is kept untouched.

Legal Considerations for Digital Evidence Preservation

Digital forensics investigators must follow the law when collecting digital information. Some legal considerations include:

• Admissibility rules – Courts will always ensure that digital evidence is relevant, authentic, and lawfully obtained. For example, the evidence presented in court – such as a screenshot from a smartphone containing multimedia data like photos or videos – must be proven to be authentic and unaltered.
• Search warrants and consent – Personal digital information about users may only be retrieved through the use of a search warrant or with user consent. Without proper authorization, original evidence can be ruled inadmissible.
• Jurisdictional challenges – Evidence is often kept on servers located in foreign jurisdictions. These cross-border investigations sometimes run into complications with privacy regulations, resulting in a need for outside cooperation and legal contracts.
• Regulatory standards – Standards such as ISO/IEC 27037 or NIST SP 800-101 can provide guidelines for law enforcement and forensic experts to consistently preserve data from different sources. Following these regulator standards improves the credibility of evidence presented in court.

Challenges in Preserving Evidence

While preserving digital evidence, several challenges may arise, including:

• Use of encryption and passwords – Many files and electronic devices are password-protected and encrypted. Gaining access usually requires specialized processes or new tools designed for decryption.
• Data volatility – Data stored in a computer’s random access memory (RAM) or caches can vanish the instant the computer is turned off. Volatile data, in particular, must be captured quickly with the right tools to avoid losing evidence vital to a case.
• Cloud and remote systems – Stored remotely, digital evidence requires instant access and, in some cases, special permission. Additionally, secure transfer protocols must be followed to prevent the loss of essential data.

However, investigators can follow some best practices to prevent evidence from being permanently lost, damaged, or inadmissible:

• Forensic copies must be created without delay.
• All preservation tasks must use validated and standardized tools.
• Thorough documentation alongside audit trails must be maintained.
• Regular training must be conducted for personnel on procedures for handling digital evidence.

Adhering to these best practices helps safeguard the integrity and reliability of digital evidence preservation throughout its lifecycle.

How New Technology Affects Digital Evidence Collection

Changes in technology are also influencing how digital evidence is preserved. For instance, advances in technology are creating new methods of preservation and evidence collection, that will be essential in shaping the future of digital forensics.

These technological advances include:

• AI and automation – Automation and AI are now more commonly used in digital forensics to help filter, analyze, and categorize large volumes of data. Machine learning can analyze data, find patterns, spot anomalies, and retrieve pertinent evidence far more efficiently than in the early days of forensic technology.
• Blockchain – Blockchain has been proposed as a solution to the issue of ensuring a proof of custody for evidence by utilizing a decentralized and unchangeable ledger. Blockchain can log every single transaction or access to a piece of evidence, which can provide investigators with a structured history that is unchangeable and able to be audited. Although Blockchain is still in the experimental phase in most places, it offers potential improvements in preserving evidence integrity and protecting crucial data.

Digital evidence preservation continues to evolve, posing unique challenges for law enforcement and legal professionals. To keep up with modern digital investigations, agencies must adapt their training programs and use sophisticated tools and technologies.

With the ever-increasing reliance on cloud platforms, artificial intelligence, and mobile technologies, the methods used for evidence preservation have now evolved alongside the tools themselves. These shifts also introduce new challenges, ranging from safeguarding multimedia data to ensuring that key evidence gathered from different sources maintains evidence integrity in the courtroom.

Today’s forensic professionals must apply the best tools to secure digital data, document every step of evidence preservation, and collaborate closely with legal teams and police investigators. Whether the task is recovering deleted files, investigating criminal activity, or analyzing computer crime through network forensics, the ultimate responsibility is to protect the truth.

The B.S. in Criminal Justice at AMU

For adult learners interested in digital forensics and other criminal justice topics, American Military University (AMU) provides an online Bachelor of Science in Criminal Justice. For this degree program, students can take courses involving a variety of topics, include criminology, criminal investigation, and crime analysis. This major also has a digital forensics concentration, enabling students to take courses in computer forensics, cybercrime, and digital forensics investigation procedures and response.

Want more details? Visit AMU’s criminal justice degree program page.

Note: This degree program is not designed to meet the educational requirements for professional licensure or certification in any country, state, province or other jurisdiction. This program has not been approved by any state professional licensing body and does not lead to any state-issued professional licensure.

FTK Imager is a registered trademark of Access Data Group, Inc.
Encase is a registered trademark of Open Text Holdings, Inc.
Axiom is a registered trademark of Magnet Forensics Investco, Inc.
X1 Social Discovery is a registered trademark of X1 Discovery.