Former Istanbul prosecutor Sadrettin Sarikaya has been held in solitary confinement for more than 500 days, according to his son.

Sarikaya, the prosecutor who had called the intelligence chief Hakan Fidan for testimony as part of a 2012 investigation into the outlawed Kurdistan Workers’ Party (PKK),  was dismissed from the post over his alleged ties to the Gulen movement and jailed pending trial in February, 2017.

“Enough is enough. My father Sadrettin Sarikaya has been kept in one-person cell for 500 days. Even though you are not providing fair trial, show some mercy. This amounts to torture,” his son Seyfullah tweeted on Monday.

Turkish government blames Gulenists for the July 15, 2016 failed coup while the group denies involvement.

More than 150,000 have passed through police custody and 90,000 have been arrested over ties to the movement since the summer of 2016.