Ok Im new to HR and so too my organisation in the sense of having a HR department. We have an employee who made a minor mistake and was picked up on it by their line manager (at most a verbal warning) and their reaction was over the top and they informed the line manager that they were actively looking for another job. January is our busiest time (so employees expect to be busy), they also expressed that they have been working over-time (expected at this time) and said we were not addressing the situation which we are. We are training more people to do their role and hiring more employees which had been doing for some time in preparation for busy periods. The manager wants them to leave after this info however that cannot be done like that. My question is where do we stand as the employee deals with alot of sensitve information and if they were to go to a competitor it would be a major conflict of interest. The employee left over 2 years ago and then came back however we don't think they signed a new contract, it was left as the original one.