Detectives investigating the murder of Barry McCrory (35) have been granted an additional 36 hours to question a suspect who was arrested near his home in the Galliagh area of Londonderry in the early hours of Wednesday morning.
Weapons were also recovered during the arrest and follow-up operation.
Mr McCrory was shot dead in his girlfriend's flat in Shipquay Street in the centre of Derry last Thursday morning.
The killer is thought to have got into the building through a communal door before forcing his way into the flat and shooting Mr McCrory in the head and chest.
He is thought to have died almost immediately.
The detained man, Kieran McLaughlin (58) from Elaghmore Park, was brought by armed police officers to the city Magistrates Court for the detention application from Antrim PSNI station, where he has been in custody since his arrest.
Uniformed police officers as well as members of the PSNI's tactical support group were both inside and outside the courtroom for the application being made by a detective constable in the major investigation unit based at Maydown on the outskirts of Derry.
He told District Judge Barney McElholm that the application was for an additional 36 hours to allow detectives to further question the detainee.
Questioned by his solicitor Kevin Casey, the police witness confirmed that McLaughlin had been detained under the Police And Criminal Evidence Act and not under terrorist legislation.
When asked by Mr Casey why McLaughlin had been transferred after his arrest "on a whim" to Antrim police station rather than being detained in Derry, the detective constable said that decision had been taken by the senior investigating officer in the case.
He believed the interviewing facilities in Antrim were superior to those available in Derry.
The witness said detectives did not start to interview the detainee until 8pm on Wednesday.
This was 17 hours after his arrest and because of the fact that medical assessments had to be carried out.
Mr Casey said the decision to transfer Mr McLaughlin to Antrim was not conducive to an expeditious police investigation.
The Resident Magistrate granted the 36-hour detention application which he said started at 11.57 yesterday morning.