Kittlaus has led the speech recognition efforts for Apple since it bought Siri in April of 2010.
He had been Siri’s CEO since 2007. Before that, the Norwegian-born Kittlaus was an entrepreneur in residence at the Stanford Research Institute and also worked at Motorola.
Kittlaus apparently left after the launch of Siri, but sources said other key Siri execs were expected to remain at Apple.
Apple did not immediately respond to a request for comment.