Police in Northern Ireland have arrested a man on suspicion of the murder of Sean Small, an 84-year-old who had recently served a prison sentence for sex offences.

The suspect, in his 40s, was detained on Tuesday two days after Small’s body was discovered outside his home on Slievenabrock Avenue in Newcastle, County Down.

Police said the victim was last seen alive on 19 August and at some point between then and 24 August he had sustained a “brutal and sustained attack”.

In 2022, Small pleaded guilty to 10 sexual offences against a woman described as “vulnerable” and a teenage girl. He was sentenced to three years in prison and three years under supervision in the community, and had recently returned home.

Police said they had an open mind about the motive for the incident and asked the public to not speculate. A postmortem is under way to establish the time and manner of death.

“I know the local community will be in shock following the news of this crime,” Det Ch Insp Kerrie Foreman told reporters on Tuesday. “Detectives are working as quickly as possible to understand how and why this has taken place.”

She confirmed there had been an incident of criminal damage at Small’s house several weeks ago. He lived on a quiet, residential street in the seaside town.

Crimestoppers have offered a reward of up to £20,000 for information that leads to arrest and conviction of those responsible for the murder.

The mother of one of Small’s victims told the Belfast Telegraph that neither she nor her daughter had been notified of his release but there had been a rumour in recent weeks that he was out of prison.