The PSNI have released one of two men arrested in connection with the murder of Emmett Shiels in Derry on Tuesday morning.
The 33-year-old man and a 17-year-old youth both presented themselves for questioning at a PSNI station in Derry on Tuesday night.
The teenager remains in custody.
Mr Shiels, 22, was shot dead in the Creggan area early on Tuesday morning after apparently intervening in a row between a group of masked men and local youths.
Dissident republicans are being blamed.