People with information concerning the murder of 29 year-old journalist, Lyra McKee, are said to be living in fear after pro-I.R.A. graffiti threatening anyone passing information on to the P.S.N.I. with execution appeared in the city overnight.
Three slogans, in total were daubed onto the facade of a community building called the Old Library Trust.
The messages read: 'IRA is here to stay', 'Informers will be executed' and 'IRA'.
The Old Library Trust building is located several hundreds metres away from where Ms. McKee was shot dead when a masked 'New I.R.A.' gunman opened fire on two heavily armoured P.S.N.I. vehicles on April 18.
The threat to murder anyone passing on information to the P.S.N.I. came a few hours after police investigating the murder of Lyra McKee confirmed they would guarantee anonymity for anyone who comes forward with evidence that could be used in a future criminal trial.
One local person who asked to remain anonymous said the slogans "have put the fear of God" into the community.
"It's very tense in Creggan at the moment and the carry on overnight has put the fear of God into people living here," said the local resident.
"People want to do the right thing but when you see stuff like this going up it's understandable why they decide not to," the resident added.
People in Londonderry, Northern Ireland and the rest of the world condemned the the death of Ms McKee and told those responsible they were "not wanted here anymore".
Ms. McKee was laid to rest after a funeral service in St. Anne's Cathedral in Belfast on April 24.
The gifted writer was planning to propose to her girlfriend, Sara, while on holiday in New York later this month.