Loss of confidence & trust

Scenario: the company has been investigating about a reported fraud issue of a manager. the manager came to know abt this confidential matter because a staff who was deeply involved in the investigation shared it with his subordinate bec of trust but the latter shared it with the involved manager. My question is that; is there sufficient ground to terminate the staff who was involved in the investigation bec of sharing an info to the subordinate but was not liable for spreading the rumor?Although this is an internal matter, staff who was involve in the investigation is in- charge of external confidential matters? Again, is this a misconduct and a just cause for termination?

please enlighten me on this...I really need your advice!!!

if it was not motivated by an ill motive, i would not recommend termination, but a lesser penalty

if in case the company should pursue termination and or the lesser penalty should be forcing the staff to resign even without proving that there was an ill-motive, what is the best thing that the staff should do?

please advice!!!

they should file a case of illegal termination at nlrc