Concerns about staff
The Prevent Duty Guidance applies to staff as well as students. Much of the information on the University Prevent web pages refers specifically to students, but the advice can be applied to situations involving staff members as well.
Notice, Check, Share
If you were worried about a colleague for any reason, you would probably talk to them or talk to your line manager to share your concern. The process is the same for any concerns. You do not need to diagnose the problem - it is highly unlikely to be Prevent-related, but please do share concerns so the colleague in question can be offered support with whatever issues they may be experiencing.
HR staff have attended a Prevent briefing and can advise on how to deal with difficult situations.
The Prevent Lead can offer advice whether the concern is about a student or a member of staff.