Generally speaking, you are under no obligation to report a crime, especially if you are not a witness. If you are on probation or under any other ethical duty to report a crime, that changes things.
Who is pressuring you and why?
You seem to be describing hearsay within hearsay. First, you have no obligation to report on what you have heard might have happened. This would not preclude you from choosing to cooperate with an investigation if asked, but you are not under any obligation to do so. How can you be bullied to say something you say you did not see, but were rather only told somebody else saw?
It sounds like you are being asked to speculate and by your own admission, you did not see anything. My best advice would be to say nothing as it seems you are uncomfortable and are being dragged into somebody else's issue.
Good luck and keep a calm perspective.
This answer is marginal legal advice and does not constitute an attorney-client relationship. Every client and case is unique. The best advice is to always consult with an attorney. Free legal resources at www.ZippToCourt.com