Modern network logging an analysis tools can play back ALL network activity going back days. I have seen a VoIP call reconstructed (NOT from www access log files.) and played back as high quality audio using network logging tools which are standard for many large corporates, including the aviation industry.
The comments above about what your company IT people may be able to do are spot on.
If you need to whistle blow, do it from outside the building, and not on your own machine.