Complex sentence: Olof Palme did not hear about the plans until at home, at 6:30 pm, when he met with his wife, by which time Palme had already declined any further personal bodyguard protection from the security service.
Split into simpler sentences: Olof Palme did not hear about the plans until at home, at 6:30 pm, when he met with his wife. By which time, Palme had already declined any further personal body guard protection from the security service.