What are the stages of a criminal investigation?

A criminal investigation begins when the police suspect a crime may have been committed. The police investigate to discover if a crime has been committed and by whom. The police conduct the investigation, gathering evidence and may charge suspects with a crime. The police then report to the Public Prosecution Service (PPS), who usually decide what, if any, charges are suitable.

If the police identify you as a suspect they might arrest and interview you as part of the inquiry. A key stage is the decision to arrest.

After a period in custody for questioning, the next key stage is the decision to charge. If the police decide you should still be kept in custody, you will be taken to a court who will decide whether or not to release you on bail before the trial.

Important notes:

If you are being investigated for alleged terrorist offences your rights and the police powers are different from those discussed below (see the Terrorism Act 2000 which is outside the scope of these factsheets);
If you are under 18, there are some additional safeguards of which you should be aware. You should ask the lawyer to explain carefully the procedures that will be followed in your case.

For more information, click on the links below:

Investigation and arrest (1)
Interview and charge (2)
Court appearance before trial (3)
Preparation of case before trial (4)

Investigation and arrest (1)

Will the police ask me questions?

If the police think that you may have committed a crime or have information about a crime, they can ask you questions to help their investigation.

Must I go to a police station?

The police can stop you, search you and ask you questions in the street or other public place. If asked, you should tell the police your name and address. If the police suspect you of a crime, they may ask you to go to a police station voluntarily. They also have the power to arrest you on reasonable suspicion and take you to a police station against your wishes. They must tell you why they are doing so.

Am I free to leave the police station?

If you are at a police station, either as a suspect or possible witness, but have not been arrested, the police must tell you that you are free to leave whenever you wish.

What is arrest?

Arrest means placing you under detention for the purpose of enforcing the law. If the police want to keep you in the police station against your will they must arrest you.

What happens once I am arrested?

If you are arrested the police must tell you the reasons why. The police must also explain why they have arrested you and must caution you. You must be taken to the police station as soon as possible. Once you arrive at the police station the custody officer will decide whether your detention should be authorised.

What happens if I do not speak the language?

If you do not understand the language, the police must get an interpreter for you. The interpreter will be free of charge.

Can I have a lawyer?

If you are arrested, you have the right to have a lawyer to help you. If you do not know a lawyer the police will provide you with names of solicitors you may contact and who are willing to give advice. For more information see Getting legal advice.

Can I contact someone to inform them that I have been arrested?

Yes. You have the right to tell someone that you have been arrested. The police will permit you to make a telephone call for this purpose.

Can the police search me?

Even if you are not under arrest the police have the power to stop and search you or your vehicle but only if they have reasonable grounds for suspecting you have stolen or prohibited articles. If you have not been arrested you do not have to provide blood or other samples, and the police cannot take your fingerprints without consent.

If you have been arrested the police can search your clothes and bags and can also seize these items for evidence. The police can also take your fingerprints and get permission to take samples from parts of your body, for example blood, saliva or other body tissues.

Police may retain your fingerprints or samples if taken during the course of an investigation and police suspect your involvement in the offence. This applies even if you are not prosecuted or convicted of the offence.

Must I take part in an identification parade?

If you have been arrested the police can require you to take part in an identification parade. Normally a parade consists only of video photographs being shown to the suspect. The duty solicitor can help you if a parade takes place.

Can the police search my car or premises?

Yes. Once you have been arrested the police may enter and search any premises in which you were located when arrested or immediately before being arrested for evidence relating to the offence. The police can also search any premises or vehicle on reasonable suspicion and remove property if it is relevant to the investigation, but only with authority from a senior officer.

Can I see a doctor if I need one?

If you need medical help you have the right to see a doctor. You should tell the police why you need medical help.

What if I have a recognised physical or mental health condition?

If you suffer from a recognised physical or mental health condition, the police must ensure that all necessary measures are put in place to address the issue including the attendance of an appropriate adult where appropriate.

I am from another Member State. Can I contact my Embassy?

If you are from another country, you have the right to contact your Embassy for help. In some cases, this is automatic. A representative from the Embassy will come to the police station or contact you to see if you need help.

What happens if I am arrested on a European Arrest Warrant?

If a European Arrest Warrant is issued by one Member State, you can be arrested in another Member State and sent back to the country concerned after a hearing before a judge. You are entitled to have a lawyer and an interpreter if you need one.

When will the police charge me?

If the police think that there is enough evidence against you, they can charge you with a crime. The charge informs you what crime the police think you have committed. Once you have been charged the police cannot question you further about that crime. However, when you go to trial the prosecutor may charge you with a different crime.

How long can I be detained by the police after arrest?

Once you are arrested the police can detain you at a police station for up to 24 hours. A senior officer (superintendent) may extend this period to 36 hours if he has reasonable grounds for believing that detaining you is necessary to secure or preserve evidence, the offence is a serious one and that the investigation is being conducted diligently and expeditiously.

After that time you must be charged with an offence or released from police custody without charge. If the police wish to detain you further they must obtain permission from a Magistrates' Court. The court can extend the period up to 72 hours. If police want to detain you for yet longer, they must return to the Magistrates' Court for permission to do so. The maximum detention period in total is 96 hours.

For your rights to legal assistance during this stage of the proceedings see Getting legal advice.

Complaints against the police

If you think you have been treated inappropriately by the police, you may complain to the Police Ombudsman for Northern Ireland. You should ask your lawyer to take this matter up on your behalf.

Interview and charge (2)

When can I be interviewed?

If you are detained at a police station under arrest, the custody officer must ensure that you are fit enough, both mentally and physically, to be interviewed. In any period of 24 hours during which you are detained you must be allowed a continuous period of at least 8 hours for rest, free from questioning, travel or any interruption in connection with the investigation. During an interview you should generally be permitted 15 minute refreshment breaks every 2 hours.

Must I answer the police's questions?

You do not have to answer any question which the police ask you. If you are a suspect the police have to give you a formal warning (a caution) before they ask questions. The caution warns you that you do not have to answer questions but that, if you do say anything, what you say can be used as evidence in court. You must also be told that if you fail to say something that you later rely on in court then the fact that you did not mention it to the police may be used as evidence against you.

How are police interviews conducted?

If at a police station the interview will take place in an interview room. The interview will normally be conducted by the police officer investigating the offence and will normally be tape-recorded. The recording process must be explained to you before interview. You will be entitled to select one of these cassettes at the end of the interview and the other tape will be stored by the police.

When will the police charge me?

If the police think that they have enough evidence against you, they can charge you with a crime. Once you have been charged the police cannot question you further about that crime. The charges may be altered at a later stage in the process.

Court appearances before the trial (3)

When do I first appear in court?

If you have been held in police custody, you must be taken to court on the next day it is sitting. Normally, the first hearing will be in the Magistrates’ Court (where the case will be dealt with by a District Judge).

Do I have the right to a lawyer?

You have the right to a lawyer in court. See Getting legal advice.

Will there be an interpreter if I don't speak the language?

If you don't speak the language then an interpreter will be provided for you, free. The interpreter will translate the charges against you and all of the court proceedings.

Can I be released from custody?

If you are held in custody, whatever crime you are charged with, you can apply to the court to be released on bail. You will normally be granted bail unless there is a risk of further offending, a risk of interference with witnesses or a risk of you not attending court on the next occasion. Bail may be granted subject to conditions, such as that you must reside at a certain address and must stay at home during certain hours. You must attend court as and when required for your bail to be renewed. If the court refuses bail, you will be taken to prison until your trial.

Can I appeal the decision to keep me in prison until the trial?

If you are refused bail in the Magistrates’ Court, you are entitled to apply for bail afresh in the High Court. Your lawyer will advise you on this matter and will prepare the necessary documentation for the new application to be made.

The High Court will normally be able to hear your application within a matter of days from the refusal of bail by the Magistrates’ Court. If you are refused bail by the High Court, a further application can normally be made only where there has been a change of circumstances or where new information is brought to the Court's attention.

Will I appear in court again before the trial?

There will usually be a number of occasions on which your case will be listed before the court again before your trial. Your lawyer will explain this to you in more detail and will advise you on what needs to be done at each appearance.

How long can I be held in prison before the trial?

This will usually depend on the nature and complexity of the case. While there are not strict statutory time-limits for bringing cases to trial in Northern Ireland, the European Convention on Human Rights entitles you to a fair trial within a reasonable time. Your lawyer will advise you of the appropriate steps to be taken if your case is not brought to trial within a reasonable time.

Preparation of the case before the trial (4)

What happens before the trial?

In the period before your trial, the PPS continues to review whether the case is strong enough to justify going to court. Their evidence must be shared with your lawyer. You and your lawyer will be entitled to see all the evidence that the prosecution will use against you at trial. For example, if witnesses are to give evidence against you at the trial, you will be given the written statement of each witness.

The prosecution must also disclose to you any material that may weaken the prosecution case or assist your case. They must continually review the evidence and disclose to you any material falling within that test.

I am from another Member State. Do I have to be present in Northern Ireland before the trial?

If you are not being held in custody, you are free to go back to your own country, unless the Court has attached a condition to your bail that you must remain in Northern Ireland. You must, however, appear at Court when required to answer your bail and for your trial. Failure to do so is a criminal offence.

If there is a condition attached to your bail that you must remain in Northern Ireland, you can apply to the Court for this to be varied. For some preliminary hearings, your lawyer can ask the Court not to require your attendance. If you are in any doubt about your entitlement to leave the jurisdiction, you should seek your lawyer’s advice on the matter.

Will my case always go to trial?

There must be enough evidence to justify bringing the case to court. It is possible that the PPS may decide during the pre-trial stage that there is not sufficient evidence, or that it is not in the public interest, to go to trial in relation to some or all of the charges. If this happens then some or all of the charges against you may be withdrawn.

What kind of evidence will the prosecution collect?

The police will interview witnesses in the case and may also collect physical and forensic evidence. For example, they may collect documents from your home or place of work, they might search your car or collect samples of your DNA (e.g. hair, saliva etc).

Can I prevent the prosecution from collecting certain evidence?

Sometimes the police have to obtain a search warrant, but that can be challenged. Usually warrants have to be specific about what can be searched and why. If the police search in places not authorised by the warrant, then the evidence that they collect might not in some cases be allowed in the trial.

Will information be requested about my criminal record?

The prosecution will gather information about your criminal record, including convictions from outside the UK.

Can the charges against me change before the trial?

Yes. This depends on the prosecution’s assessment of the evidence available. Your lawyer can suggest that it would be appropriate for the charges to be changed.

What happens if I have been tried for the same offence in another Member State?

If a final decision on the same facts has been made by a court in one Member State then you cannot be tried again on the same facts in another Member State.

Can I plead guilty before the trial?

Yes. If you have pleaded not guilty in the first instance you can change your plea to guilty at a subsequent hearing. It is an important principle that a plea of guilty must be voluntary: you will, of course, be advised by your lawyer on the strengths and weaknesses of the prosecution case, but ultimately the decision on whether you plead guilty is a matter for you.

Defendants (criminal proceedings)