Fethullah Gulen has been called Turkey's second most powerful man. He is also a recluse, who lives in self-imposed exile in the US.
An apparent power struggle between his followers and those around the Turkish Prime Minister, Recep Tayyip Erdogan, has reached a new pitch of intensity and loathing.
Since arriving in the US in the late 1990s, Mr Gulen, 74, has not given a single broadcast interview. What rare communication there has been with the media has almost exclusively been conducted via email.
But now, the BBC has had exclusive access to the Muslim cleric. I travelled with Guney Yildiz from the BBC Turkish Service to a remote part of Pennsylvania to meet the man.
In the interview, Mr Gulen denied using his influence to start investigations into alleged corruption among senior members of Mr Erdogan's AK Party which have led to a number of police commissioners being sacked and to some of Mr Erdogan's allies being arrested.