The letter, signed by prominent Nobel laureates, urges Erdogan to return to the peace process with the Kurds, release Ocalan from prison, and enter into negotiations with him to address the Kurdish question in Turkey. 

The laureates express their concern over the conditions in Turkish prisons, particularly the place where Ocalan is being held, and accuse the Turkish government of torturing prisoners. 

They also highlight that Turkey, as a member of the Council of Europe, is violating its laws.