Fair Work Inspector can require any person, not just the person under investigation, to give them any record or document that may help them find out whether someone has contravened Commonwealth workplace laws.
A Fair Work Inspector can require a person to hand them the original records or documents, inspect them, make copies or record them, and can keep them for as long as they need to. However, they cannot legally seize the records or documents (this means they can't take records or documents without giving notice).
If they keep a record or document, they must let the person who produced it (or anyone entitled to have it), inspect and copy the record or document at all reasonable times.
In general, Fair Work Inspectors will not keep the original of a record or document unless it's not practical to make a copy.