Article 4 of Regulation 883/2013 refers to Article 1(4) for the purpose of defining the scope of the Office’s internal investigations within the institutions, bodies, offices and agencies established by, or on the basis of, the Treaties.
The Office investigates
The Office also investigates the following matters concerning officials, other servants, members of institutions or bodies, heads of offices or agencies, or staff members:
Investigations focus directly on the personnel of the European Union (EU) in the broadest sense without distinction by grade or function: officials, temporary staff, seconded national experts, contract staff, other staff whose employment contracts are governed by private law, i.e. staff of joint ventures or of certain agencies and staff of subcontractors working in buildings of the institutions.
Investigations also focus on members of the institutions, including those appointed by Member States or by other institutions, namely European Commissioners, Members of the European Parliament, the European Ombudsman, judges and Advocates General of the Court of Justice of the European Union, members of the Board of Governors of the European Central Bank, members of the European Court of Auditors, members of the Economic and Social Committee and members of the Board of Governors of the European Investment Bank.
Here are some examples of matters that are subject to investigation:
Any person or entity from Europe or any other part of the world may, in any language and anonymously or otherwise, report information to OLAF on serious misdemeanours relating to the performance of professional activities which have been committed by a member of the personnel of the EU or a member of a European institution if such information is liable to raise serious suspicions of fraud, corruption or any other illegal activity that may affect the financial interests of the Union.
You need not wait until you have proof - OLAF will conduct its own investigation.