Forensic Investigations

When police seize hard drives, phones, and other digital devices in a criminal investigation, they typically follow a digital forensics process designed to preserve evidence and make it admissible in court.

Typical steps include:

1. Seizure and chain of custody

The first priority is preserving evidence:

devices are bagged/labeled
every person handling them is logged
this “chain of custody” helps prove evidence wasn’t altered

Without this, evidence can be challenged in court.

2. Forensic imaging (making an exact copy)

Investigators usually do not work on the original device first.

They create a bit-for-bit forensic image (exact clone), often using tools like:

EnCase
FTK
Cellebrite UFED
Magnet AXIOM

They verify integrity using hash values (digital fingerprints like MD5/SHA-256).

If the hash matches later, they know the copy wasn’t changed.

3. Data extraction and recovery

They look for:

deleted files (often recoverable)
hidden partitions
encrypted containers
browser history
emails/messages
app data
location logs
photos/videos + metadata (EXIF)
cloud sync traces

Deleted does not always mean gone.

4. Mobile phone forensics

Phones often reveal:

call logs
SMS/iMessage/WhatsApp/Telegram/Signal data
GPS history
app usage
contacts
deleted chats (sometimes)
cloud backups

Modern phones can be difficult to unlock, but specialized tools may extract data depending on model and security.

5. Timeline reconstruction

Investigators build a timeline:

when files were created/opened/deleted
when someone logged in
device movement
communication events

This often answers who, when, where.

6. Artifact correlation

They compare across devices:

same files on laptop + USB?
same account on phone + tablet?
shared cloud logins?
browser searches matching messages?

This can connect people, devices, and actions.

7. Reporting and expert testimony

A forensic examiner writes a formal report and may testify in court as an expert witness.

Their job is not supposed to be “prove guilt,” but to present what the data shows.

Important limitations

Digital forensics can show:

a file existed
a device was used
where it was
what accounts were accessed

It cannot always prove intent or identity by itself.
For example: just because a device accessed something doesn’t always prove who was holding it.

That’s why investigators combine digital evidence with interviews, witness statements, and other evidence.

In many countries, specialist units like National Crime Agency, Guardia Civil, or FBI handle this work depending on the case type.