PSNI detectives were last night questioning four men about the death of a man in his 20s in north Belfast early yesterday morning.
Police launched a murder inquiry when the man's body was found at York Street around 4 a.m.
The four arrested all surrendered voluntarily into police custody, according to the PSNI.
The man was formally identified by his family but up to last night his name had not been released. It is not yet known how he died although police said he had not been shot.
Detectives said there was nothing at this stage to suggest that the man was a victim of a paramilitary or sectarian attack. Police have appealed for the public to assist them in their inquiries into the murder. Taxi-drivers and motorists who were in the area of York Street between 3 a.m. and 5 a.m. were particularly requested to come forward.
The SDLP Lord Mayor of Belfast, Mr Martin Morgan, expressed his shock and sadness at the death. "I hope that those responsible for this murder will be brought to justice," he said.
"With this goal in mind, I would like to call on anyone with any information on this grim attack to come forward to the police as soon as possible," he added.