Constable Michael Ferguson, 21, was shot dead in Derry in January, 1993.
A man who was arrested by the PSNI Legacy Investigation Branch with regard to the 1993 murder of a policeman in Derry has been released.
The 51-year-old had been arrested under the Terrorism Act and questioned at Musgrave Police Station in connection with the killing of Constable Michael Ferguson who was shot dead outside the Richmond Centre in Derry.
However, the man has since been released without charge.
A PSNI spokesperson said: "A 51-year-old man, arrested by detectives from the Police Service of Northern Ireland's Legacy Investigation Branch, investigating the murder of police officer Michael Ferguson in 1993, has been released following questioning.
"The investigation continues."
Constable Ferguson, 21, was killed when on duty in Derry's Shipquay Street around 2pm on Saturday, January 23, 1993.He, along with two other officers, had been attending a call at the city's Richmond Shopping Centre.
While his colleagues were inside, a gunman approached him from behind and fired two bullets into his head.
In December 2015, Christopher O'Kane from Derry pleaded guilty at Belfast Crown Court to assisting offenders in relation to Constable Ferguson's murder.
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