A man is being questioned by detectives on suspicion of murder after the body of a pensioner was found in a flat.
The alarm was raised by a resident who was concerned about their elderly neighbour, believed to be a man aged in his 60s or 70s, and officers rushed to the block of flats in Brighton to discover the body.
A spokesman for Sussex Police said the death was being treated as suspicious and a murder investigation had been launched.
"At about 5.30pm on Bank Holiday Monday police went to a flat in Vernon Terrace, Brighton, after a member of the public reported concern for the occupant at that address," he added.
"On entering the property officers found the body of a man, who is believed to be the elderly occupant.
"The death is being treated as suspicious."
A 49-year-old local man was arrested that same afternoon on suspicion of murder and is still in custody being questioned about the death.
A post mortem examination was expected to take place on Thursday while murder squad detectives were still trying to trace the man's relatives.
"We believe that deceased and the person in custody were known to each other. Inquiries are at an early stage but we are not looking for anyone else in connection with this death at this time."