Task: Question Answering
Input (English): Passage: In Depression-era North Carolina, George Pemberton is an ambitious timber baron who meets Serena Shaw, a young woman with a sad past. He falls in love with her, they marry, and Serena comes with George to his land. There, she starts taking control of things, pressuring and questioning George, while remaining affectionate towards him.
George's business partner Buchanan feels threatened by her, as she begins to exceed his authority. Things grow worse between George and Buchanan, and Buchanan strikes a deal with the local sheriff, who wants to buy George's land to make a park. George is hurt by Buchanan's betrayal, and Serena convinces George that Buchanan was never his friend.
The next day, they both go shooting alone from the group attempting to flush out a bear. After some snide remarks from Buchanan, George contemplates killing him only to hesitate and be seen by Buchanan. As Buchanan cocks his rifle, George fires first and shoots him in the chest. Campbell, George's worker, witnesses the murder, but denies it when Sheriff McDowell inquires. The death is ruled an accident. Serena consoles George and justifies his actions.
One day, he sees his illegitimate son, Jacob, posing with his mother, Rachel, for a picture. He feels responsible for the boy, and since Rachel never asked for anything, he begins giving sums of money in envelopes to her for Jacob. Serena remains unaware of this, though she does consider Rachel and the baby a threat.
One day, an accident occurs in the forest and Galloway, a mysterious worker, loses his hand to an axe swing. Serena rushes to help him and uses a belt as a tourniquet to stop the bleeding which saves his life. Having problems with her pregnancy, Serena and George rush to the hospital after Serena experiences heavy bleeding and pain. She miscarries. They learn that she can never again bear children. Things continue to grow worse, and Rachel's baby becomes more obvious to Serena. 
Question: What is the occupation of the man who murders Buchanan?
Output (English): timber baron.