Detectives are today questioning a man about the death of a householder at his home in Felpham, near Bognor.
The 61-year-old man was discovered yesterday afternoon lying on the floor at the foot of the stairs at his home in Canning Road, Felpham.
Police are treating his death as suspicious and have arrested a 51-year-old man who was today still being questioned by officers.
A post mortem examination was being carried out today to try to establish the cause of death.
Det Insp Neil Fellingham, based at Chichester, said: "We have a team of detectives working on the case today.
"We are treating it as a suspicious death.
"We have a man in custody who we will be questioning today."
A spokesman for Sussex Police said: "There has been no identification of the man at the moment but we believe he was a resident of that address."
Detectives are currently trying to track down the relatives of the man to inform them of the death.
Investigating officers and forensic experts were today inside the house examining the death scene.
Police will also be speaking to neighbours to see if they can help with the inquiry.
Det Insp Fellingham said: "The investigation is in its very early stages and the whole team will be working very hard today.
"The post mortem was being carried out at midday and we will know more when we have those results."
The area surrounding the house was today cordoned off as police carried out their enquiries.
Police confirmed that the arrested man is local to the area.
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