Where the line usually gets crossed
Commercial bribery is about private relationships rather than public officials: a benefit given to someone who owes duties to an employer, in exchange for influence over which vendor is chosen, which invoice is approved, or which terms are agreed. What turns an arrangement into an allegation is almost always concealment. The payment ran through a relative or a side company, the consulting agreement had no visible work behind it, the invoices described something other than what happened, or the relationship was never disclosed to the employer. Both the person paying and the person receiving can be exposed, and the same facts usually also support claims by the employer and termination of the contract.
The internal investigation comes first
In most matters the company acts before anyone outside does, through its own counsel or an outside firm brought in to interview employees. That lawyer represents the company, not you, even when the introduction comes from human resources and the tone of the meeting is friendly. What you say there goes to the company, and from the company it can go further. The other frequent misstep happens before the interview: deleting messages, clearing a phone, or tidying an inbox. Those steps are visible in system records and they reliably make a manageable situation worse.
What to gather and what we sort out first
Collect your employment agreement, the policies you acknowledged, and any conflict or gift disclosure you filed. Add the approval records for the vendor in question, along with the invoices and payment records. Preserve the communications themselves, on personal devices as well as work ones. In a first conversation we work out whether the company currently treats you as a witness or a subject, what obligations you still owe it while this is open, whether your own conduct is the issue or someone else's, and how likely it is that the matter stays internal, becomes a civil dispute, or reaches prosecutors.