Twenty-nine inmates escaped from the prison in the early hours of March 25, 1988, as it was still being administered by the military. Of the escapees, eleven were sentenced to the death penalty and eight to life imprisonment. They were all members of illegal extreme left-wing organizations, such as 19 members of the armed wing of the Communist Party of Turkey/Marxist–Leninist (TİKKO) – considered as extremely dangerous – three members of the Revolutionary Communist Party of Turkey (TDKP/HK), one member of the Turkish Liberation Front (THKP/C), one member of the Revolutionary Left (Dev-Sol), and five members of the Revolutionary Path (Dev-Yol).
The mass prison break took place through a 60 m (200 ft)-long secret tunnel, which was built in six months. The tunnel was dug up manually with spoons, and the extracted soil was dumped into the sewage system