Can you be asked to testify against yourself?
No one can force you to give information against yourself, even if you are charged with a very serious offence. In Slovakia, the police have to inform you about this right at the beginning of your interrogation (in Slovak výsluch). You have to be careful of what you say because this information may later be used in court against you.
However, you have to give truthful information about your identity, such as your name and surname. A police may also examine you and take samples such as fingerprints and DNA. If the suspect or accused person refuses to provide them, the fingerprints and DNA sample may also be taken against that person's will. In such a case, a written order of a prosecutor or judge is required. It is also possible to order a blood sample collection.
What human rights violation may there be?
If you are forced to speak against your will or testify against yourself, it may result in a violation of the right to fair trial. Read more about the right to remain silent.