In some cases, the police will ask someone who has witnessed a criminal offence to make a statement. You can present yourself as a witness and give as many details as possible. Ask the police officer for his name, so that you can phone him if you suddenly remember something you forgot in your statement. During proceedings the court may also wish to hear witnesses. Witnesses who have been summonsed are obliged to appear and to tell the truth; failure to do so is a criminal offence. Witnesses who believe that they are at risk can ask to be excused from attending.