A bribery investigation can begin in many ways. Information may have been given by an employee, a related person, someone who heard something, another authority or from someone who remains anonymous throughout.
It is unlikely that a bribery investigation would be launched unless the investigators had already decided that the alleged offence was sufficiently serious to pass the ‘interests of justice’ test. That does not mean a prosecution is a foregone conclusion but the complications of such an investigation and the very serious repercussions of an adverse court decision makes taking expert legal advice as early as possible an essential decision. Being represented does not imply guilt and does not suggest you have something else to hide. The message it sends is that you want to have this addressed professionally.
Any business with shareholders needs to demonstrate to its owners that it is dealing with problems professionally and the taking of expert legal advice is part of that process.