Detective Superintendent Nick Wallen of West Yorkshire Police speaking outside the Old Bailey in London after Thomas Mair was found guilty of the murder of Labour MP Jo Cox, as her father Gordon Leadbeater (centre right) and widower Brendan Cox (centre left) look on. (Photo by Philip Toscano/PA Images via Getty Images)
Former detective superintendent Nick Wallen, of West Yorkshire Police, outside the Old Bailey in London after Thomas Mair was found guilty of the murder of Jo Cox. PA Images via Getty

Jo Cox murder probe detective raises fears over the hunt for accomplices