Police in Belfast are investigating whether one of Northern Ireland's largest sheep producers was killed by a hitman hired by a group of jealous farmers.
Patrick Devine was shot nine times at his farm in Claudy, County Londonderry, in September 2004.
Relatives found his body near a window where he had been eating a meal.
In a fresh call for new information, Beflast police are now looking into the possibility that professional jealously led to a group of farmers paying for a gunman to kill Mr Devine.
Detective Chief Inspector Gary Crawford said investigations at the time of the killing indicated Mr Devine was shot because of his success and wealth.
"A lot of members of the farming community have condemned what took place, but a small number were involved and conspired together to get rid of him," he told the Belfast Telegraph.
"Patrick was a wealthy man who had built up his wealth through hard work over many years. I believe that people were jealous of him and there were other petty squabbles," he said.
DCI Crawford said he was confident the murder was a contract killing carried out by dissident republican group, the Irish National Liberation Army.
A "significant forensic development" had brought the police closer to solving the case although police are still searching for the .22 rifle used in the murder, he added.
Anyone with information can contact to police directly on 0845 600 8000, through Crimestoppers on 0800 555 111 or on website www.crimestoppers-uk.org.