A man is being questioned following the discovery of a body in a park in Eastbourne.
Sussex Police officers were called to St Anne's Park, off The Avenue, at 2250 GMT on Thursday following a 999 call.
The body of the man, who was in his 50s, was found close to a bench.
Police said he had suffered head injuries, but that the exact cause of death would not be known until after a post-mortem examination had been carried out.
Chief Inspector Peter Mills, who is leading the inquiry, said the incident was being treated as murder.
Police guard
He said a local man in his 30s had been arrested and was helping police with their inquiries.
He added there was no clear motive for the crime.
Police officers were due to carry out a search of the park, and conduct house-to-house inquiries.
Other officers are guarding the park entrances.
Mr Mills urged anyone who may have seen a fight in the park to contact police.
He said: "We are appealing for witnesses, particularly anyone who may have seen an altercation between two men in the area of the park from 2000 GMT onwards."