The UN Envoy to Bougainville, Noel Sinclair, leaves the Papua New Guinea island today completing a posting that has lasted five years.
Mr Sinclair's departure comes despite local calls for him to remain until the first autonomous elections later this year.
Mr Sinclair says during the five years he has spent on the island he has seen an enormous transformation.
He says the biggest change has been the communication between the National government and the people of Bougainville.
However Mr Sinclair says he still harbours some concerns.
"I'm concerned about the unity of Bougainville and the basis of this concern is the existence of the no-go-zone. I am concerned about the fracture in Bougainvillean society, I would have liked to see Francis Ona being a part of the peace process. I am concerned that I am leaving without his having joined the peace process. But it's not that nothing is happening, there is dialogue taking place at various levels."
Before he left Bougainville, Mr Sinclair was sworn in as a Siwai paramount chief.
His swearing in was part of a historical reconciliation ceremony attended by some six thousand Bougainvilleans.
Another highlight of the ceremony came when sworn enemies Nick Peniai and Jonathon Ngati apologised to each other and the people of Bougainville and shook hands.
Governor John Momis who also attended the gathering told the Post Courier newspaper that reconciliation fever touched him too and he stood up and apologised on his part for mistakes in the pursuit of self-determination that had cost untold suffering.
Mr Sinclair says he would have liked to have stayed for the elections but he believes they will go ahead without any problems by the end of the year.