Would also note that I don’t think Serbia extradites its citizens…
They will, at least to Spain (EU).
Serbia | European Judicial Network(EJN)
According to the Act on Mutual Legal Assistance in Criminal Matters, Serbian law distinguishes and recognizes the following basic forms of mutual legal assistance in criminal matters:
1. Extradition of defendants or convicted persons;
2. Assumption and transfer of criminal prosecution;
3. Execution of criminal judgments;
4. Other forms of mutual assistance.
When requesting MLA from Serbia, the requesting party must indicate the legal basis and/ or reciprocity principle upon which such request is sought. Please note, regardless of the existence of international treaties or bilateral agreements, the requested State may have expressed reservations which limits the assistance that can be realistically provided. For example, some states have retained the right to refuse to provide judicial assistance in cases where the offense is already the subject of judicial investigation in the requested country. The main principle that should be followed is: one must always take into account the fact that the requested State will have to comply with their own domestic law and internal procedures, when deciding whether and to what extent the assistance sought can be generally accorded.