Flowers and a candle are left at the exact spot where 29-year-old journalist Lyra McKee was shot dead, in Londonderry, Northern Ireland April 20, 2019.
Mr Murphy conceded there remains fear of reprisals from the shadowy gunmen for giving information to police.
Her death, which follows a large auto bomb in the city in January, raised fears that small marginalized militant groups are trying to exploit political tensions caused by Britain's decision to leave the European Union.
Northern Ireland Secretary Karen Bradley was among those signing a book of condolence opened at the city's Guildhall, describing her death as a "tragic loss" of one with such potential.
Police described the shooting as a "terrorist incident" and believe the violence was orchestrated in response to an earlier search by officers aimed at averting imminent trouble associated with this week's anniversay of Easter Rising.
SDLP leader Colum Eastwood has written to Taoiseach Leo Varadkar and British Prime Minister Theresa May following the killing of the young journalist urging for talks to start this week to restore powersharing.