Fletcher Pilditch, assisting the coroner, said Mr Nelson felled the tree that struck Mr Epapara causing fatal injuries.
Mr Epapara and Mr Nelson worked for logging company Complete Logging and became good friends, he said.
They were working in the same area with a group of other workers, when the incident happened.
Mr Nelson admitted that what happened would stay with him for the rest of his life.
"There's rarely a day that goes by when I don't think of him," he said.
Mr Nelson maintained that before he felled the tree he specifically radioed another colleague, Nepia Te Rangi, asking where Mr Epapara was located and whether he was near the trees at the end of the track.
He couldn't see Mr Epapara so relied on Mr Te Rangi to check whether Mr Epapara was away from where the tree would fall, he said. To his question, Mr Te Rangi had given him the all clear, followed by another all clear by someone in the background, Mr Nelson said.
However, Mr Te Rangi stated otherwise, saying he told Mr Nelson more than once that he could not see Mr Epapara.
Murray McKechnie, the lawyer acting for Mr Epapara's family, asked Mr Te Rangi why he did not tell Mr Nelson to stop felling the tree.
It was normal procedure to say "stop" when a person was about to fell a tree but could not see where, or didn't know where his colleagues were located, Mr McKechnie said.
"Why didn't you say 'for God's sake stop, Robert's there, stop'. That one word, stop, why didn't you say it?"
Mr Te Rangi didn't respond to Mr McKechnie's questioning.
Mr Pilditch said regardless of the differences in their stories, Mr Te Rangi and Mr Nelson accepted their communication simply was not good enough.
The inquest is expected to continue today.
