For "ties with a terrorist group." Last month, the AI Chairman of the Turkish chapter was arrested for having ties with the group who spearheaded the attempted overthrow of the government; he is currently awaiting trial.
EDIT: Idil Esser was detained yesterday, along with I think nine others. This is the SECOND detainee of an AI leader in Turkey in the past month. The Chairman was a month ago. I wasn't clear in the explanation since I didn't specifically reference that this detention was of the Director except in the title. The Chairman, Taner Kilik, is a separate, older detention I didn't want overlooked since he is still waiting to go to trial.
Bumping because I edited for clarity. This is the SECOND detention of AI leadership in Turkey. The Chairman was a month ago. The Director (and others) was yesterday.