<Li> Dr. Zak Khan (Arsher Ali)--Series 14 . A junior doctor who worked his forensic science apprenticeship with the team, to learn the ropes of the profession . </Li> <Li> Wyn Ryan (Ruth McCabe)--Series 1--3 . Professor Ryan's sister, who, after coming over to visit her from her home in Ireland, ended up living with her on a permanent basis . </Li> <Li> Ricky Ryan (Matthew Steer)--Series 1 . Wyn's son and Sam's nephew, who regularly got into trouble and was expelled from school for very poor behaviour . </Li> <Li> Rosemary Mason (Jane Hazlegrove)--Series 6--7 . The main receptionist at the Lyell Centre, before the change in focus from university department to purely commercial pathology . </Li>

Who played sam ryan's son in silent witness