What Happens During the Criminal Investigation Phase?

What Happens During the Criminal Investigation Phase?

When someone receives a court summons as a suspect, it is common for them to have very little understanding of what is actually happening within the criminal process at that moment. The court has opened an investigation, procedural steps are underway, and a judge is making decisions that may directly affect their life and future. All of this takes place during the investigation phase, which is probably the least visible stage of criminal proceedings for the general public, yet at the same time the most decisive.

The investigation phase is where the foundations of the case are built. The evidence gathered, the statements given, the measures adopted by the judge, and the defence strategy developed at this stage will largely determine everything that follows: whether the case proceeds to trial, how the charges are formulated, and the position from which the accused enters the trial.

In this article, we explain in detail what the investigation phase is, how it unfolds, what procedural steps are carried out, what decisions the investigating judge may take, and, most importantly, what rights the suspect has at every stage.

What Is the Investigation Phase and What Is Its Purpose?

The investigation phase—also referred to as preliminary proceedings (diligencias previas) or summary proceedings (sumario) in more serious cases—is the initial stage of criminal proceedings in which alleged criminal conduct is investigated.

Its purpose is not to judge or convict, but to gather information and evidence to determine whether there are sufficient grounds to proceed to trial or whether the case should be dismissed.

This phase is led by the investigating judge, who acts both as the director of the investigation and as a guarantor of fundamental rights. The judge does not decide on guilt at this stage; rather, they ensure that the investigation is conducted lawfully and impartially.

A key principle governing this phase is the presumption of innocence. Being under investigation does not imply guilt. The investigation is simply the mechanism through which the State determines whether the available indications justify a trial. Many cases end at this stage with dismissal due to insufficient evidence.

How Does the Investigation Begin?

The investigation phase may be initiated through several channels:

• Complaint: filed by a victim, witness, or any individual aware of potentially criminal conduct
• Criminal claim (querella): a formal legal action requiring legal representation
• Police action ex officio: when law enforcement directly detects a criminal offence
• Public prosecutor initiative: when the prosecution identifies potential criminal conduct

Once the court receives this information, the investigating judge assesses whether the facts appear to constitute a criminal offence. If so, an order opening preliminary proceedings is issued. If not, the case may be dismissed outright.

What Procedural Steps Are Taken During the Investigation?

The investigation phase is characterised by a wide range of procedural measures aimed at clarifying the facts. Each must be authorised through a reasoned judicial decision and must comply with principles of necessity and proportionality.

Statement of the Suspect

This is one of the most important and sensitive steps. The suspect appears before the judge to respond to questions. However, they are not obliged to testify. They have the right to remain silent, refuse to answer, and avoid self-incrimination, without adverse consequences. They must also be assisted by a lawyer.

Witness Testimony

Witnesses provide information relevant to the case and are generally obliged to testify truthfully, subject to certain legal exceptions (e.g., close relatives or self-incrimination). False testimony constitutes a criminal offence.

Expert Reports

Where specialised knowledge is required, the judge may appoint experts (e.g., forensic specialists, accountants, engineers). These reports often play a decisive role and may be challenged by the defence.

Searches and Inspections

The judge may authorise searches of premises where evidence is likely to be found. Such measures affect fundamental rights and require strict legal safeguards and judicial authorisation.

Interception of Communications

Telephone tapping, email monitoring, or other communication interception measures are highly intrusive and require strict judicial authorisation based on necessity and proportionality.

Identification Procedures

Where identification is crucial, procedures such as identification line-ups may be conducted, ensuring objectivity and procedural fairness.

Precautionary Measures During the Investigation

During the investigation, the judge may impose precautionary measures to ensure the proper conduct of proceedings and protect potential victims.

The most severe is pre-trial detention, which deprives the suspect of liberty during the investigation. It may only be imposed under strict conditions (e.g., risk of flight, destruction of evidence, reoffending, or risk to victims).

Less restrictive measures include:

• Travel restrictions
• Passport surrender
• Periodic court appearances
• Bail
• Prohibition of contact with certain individuals

The judge must always apply the least restrictive measure necessary.

Secrecy of Proceedings: When and Why It Applies

As a general rule, the parties have access to the case file. However, the judge may declare the investigation confidential (secrecy of proceedings) for a limited time if disclosure could jeopardise the investigation.

This measure is exceptional and temporary. Once lifted, the suspect and their lawyer gain full access to the case file.

How Does the Investigation Phase End?

The investigation concludes when the judge considers that all necessary steps have been completed and sufficient information has been gathered.

At that point:

• The parties are invited to file charges or request dismissal
• If no charges are maintained, the case is dismissed (either provisionally or definitively)
• If sufficient evidence exists, the judge orders the opening of trial proceedings

The Role of the Lawyer During the Investigation

The investigation phase is where a skilled criminal defence lawyer can have the greatest impact on the outcome of the case.

Their role includes:

• Advising the suspect before any statement
• Ensuring procedural safeguards are respected
• Challenging unlawfully obtained evidence
• Requesting favourable investigative measures
• Contesting disproportionate precautionary measures
• Filing appeals against judicial decisions

It is not an exaggeration to say that the outcome of the trial is often determined during this phase. Waiting until trial to seek legal representation is a serious mistake.

Frequently Asked Questions

Do I have the right to know what I am accused of?

Yes. The suspect has the right to be informed of the alleged facts before giving a statement. This is essential for preparing an adequate defence.

How long can the investigation last?

The law provides indicative timeframes (generally six months, extendable in complex cases), but in practice investigations may last longer depending on the case.

Can I be investigated without knowing it?

Yes, particularly in early stages where secrecy is necessary (e.g., surveillance or interception measures). However, this cannot continue indefinitely, and the suspect must eventually be informed.

What if evidence is obtained unlawfully?

Evidence obtained in violation of fundamental rights is inadmissible and must be excluded from the proceedings. This is known as the exclusionary rule.

What happens if the case is dismissed?

If the judge dismisses the case, proceedings are closed. A definitive dismissal prevents reopening, while a provisional dismissal allows reopening if new evidence emerges. In both cases, no criminal record is generated.