49-year-old Richard Andrews' body was discovered by a member of the public last September on the banks of the River Neath.
Mr Andrews, who was from the Melyn area of Neath, was reported missing to South Wales Police in January 2018, although the last confirmed sighting of him alive was Saturday 16th September 2017.
Detective Chief Inspector Darren George, of the Major Crime Investigation Team, said: “The circumstances surrounding Richard’s death have been thoroughly investigated and we now suspect he was murdered.
“Richard was a well-known character in the Neath area, where some people may have known him by his nickname ‘Monkey’.
“Richard was a vulnerable individual and I believe he may have been taken advantage of. At the time of his disappearance it is believed he was involved with individuals from the Liverpool area, who were dealing drugs in and around the Neath and Briton Ferry areas.
“This is a direct appeal today for the local community’s help, to assist us in establishing exactly what happened to Richard, as I firmly believe certain individuals within the local community of both Neath and Briton Ferry have significant information that will assist the investigation team in bringing those who have harmed Richard to justice.
“His family have been devastated by his death and my sincere sympathise are with them.
Richard’s niece Kathryn said: “I am not saying he was perfect, I am not going to pretend he was but he wasn’t cruel. He would do anything for people, you could knock on his door and he would go to the shop in the pouring rain for you. He wouldn’t think twice about helping people.
“If someone was taken from you, you are going to want to know why and what happened.
“They shouldn’t be allowed to walk free and people should know they are dangerous.”
The independent charity Crimestoppers is today offering a reward of up to £10,000 for information leading to the arrest and conviction of the person or people responsible for the murder of Richard Andrews. You can contact the charity 100% anonymously.
The reward will only qualify if information is passed to Crimestoppers’ via 0800 555 111 24/7 or via the untraceable anonymous online form at www.crimestoppers-uk.org.
Alternatively you can call South Wales Police on 101 quoting occurrence 1800031266 or information can also be provided anonymously online via www.mipp.police.uk