(Corrections to conditions of Koçak's case in paragraphs 2, 5)

Mustafa Koçak, who was serving a life sentence over charges related to the killing of a Turkish prosecutor, died after 297 days on an extreme hunger strike where he only took sugar water.

Koçak had gone on hunger strike saying that he had been subjected to torture in police custody and forced to sign a confession, and that he had not been involved in the procurement of weapons for the killing of prosecutor Mehmet Selim Kiraz in 2015.

The legal group Halkın Hukuk Bürosu, or the People’s Law Office, on Friday announced Koçak’s death, and said their client had not been given the right to a fair trial.

“Know that the state murdered Mustafa so as not to hear a witness in court,” the group’s statement said on Twitter.

Müvekkilimiz Mustafa Koçak, ölüm orucu direnişinin 297. gününde şehit düşmüştür.



Mustafa, adil yargılanma hakkı için, hücre hücre eriyerek, direnerek ölümsüzlüğe yürüdü.



Bilin, devlet Mustafa'yı bir tanığını mahkemede dinlememek için katletti.



Anısı önünde saygıyla eğiliyoruz. pic.twitter.com/B6lFs7MtRY — Halkın Hukuk Bürosu (@halkinhukuk_) April 24, 2020

Koçak had been convicted of attempting to overthrow the constitutional order in 2017, based on testimony by a secret witness, who had testified against some 150 others, and another witness, who left Turkey after the trial and from abroad sent a petition to the court saying his testimony had been given under duress.

Another hunger striker, Helin Bölek of Turkish band Grup Yorum, died on April 3 on day 288 of her similarly extreme hunger strike, also called a death fast.

Koçak and Bölek - along with another Grup Yorum member İbrahim Gökçek, who is still continuing his protest - started their hunger strikes to demand the right to fair trial, while Bölek and Gökçek also demanded the lifting of concert bans on their band, an end to raids on its cultural centre, and for the release of imprisoned band members.

The folk collective has performed in various line-ups since it was formed in 1985 and has released 23 albums, composing some of the best known protest songs in Turkey. But it has been barred from performing since 2016 as Turkish authorities have accused members of being affiliated to the DHKP-C, a militant Marxist group considered a terrorist organisation by Turkey, the United States, and the European Union.

"All he wanted was a fair trial, they did not give him this chance. He became the latest victim of an unjust judiciary," the pro-Kurdish People’s Democratic Party (HDP) lawmaker Ömer Faruk Gergerlioğlu said on Twitter in response to Koçak’s death.