Campbell Bridges, 71, was stabbed in the heart during an ambush by a mob armed with spears and knives.
Daniel Mnene, who used to work for him, was detained earlier this week in the capital Nairobi after a tip-off from an informer.
Yesterday, he was transferred to Voi, near Tsavo National Park, where the crime took place.
He is expected to be charged with murder within days. Three men have already been charged.
Campbell was killed last August following a longrunning dispute over mining rights in the area.