I joined a company 3 years ago and hold a middle management position. A member of staff (same status, different dept.) has always been unfriendly, i.e. refusal to say 'good morning' or 'please and thank you' She has previously made a threat to me indirectly, which was relayed to me by my line manager and a member of staff. This person seems very influential to other members of staff (maybe because they are frightened of being treated the same way) Sick of the hostile environment this person has cultivated. Any suggestions on how to proceed?