After joining the Workers Party of Turkey (Türkiye İşçi Partisi), he studied law at İstanbul University in 1966. In 1968, he founded the Revolutionary Jurists Organisation (Devrimci Hukukçular Kuruluşu) and the Revolutionary Student Union (Devrimci Öğrenci Birliği).
He became increasingly politically active, and led the student-organised occupation of İstanbul University on June 12th, 1968. After the occupation was forcibly ended, he spearheaded protests against the arrival of the US 6th Fleet in Istanbul. Deniz Gezmiş was arrested for these actions on July 30th, 1968, to be released on 20 October of the same year.
As he increased his involvement with the Worker's Party of Turkey, and began to advocate a National Democratic Revolution, his ideas started to circulate and inspire a growing revolutionary student base. On November 28th, 1968, he was arrested again after protesting US ambassador Robert Komer's visit to Turkey, but was later released. On March 16th, 1969 he was arrested again for participating in right-wingand left-wing armed conflicts and imprisoned until 3 April. Gezmiş was re-arrested after leading Istanbul University Law Faculty students on a protest of the reformation bill on May 31th, 1969. The university was temporarily closed, and Gezmiş was injured in the conflict. Although Gezmiş was under surveillance, he escaped from hospital and went to Palestine Liberation Organization camps in Jordanto receive guerrilla training.
During the 60s, Gezmiş crossed paths with the infamous American Soviet/Russian CIA mole Aldrich Ames. While scouting for information on Soviet intelligence, Ames recruited one of Gezmiş' roommates, who gave him information about the membership and activities of Devrimci Gençlik (DEV-GENÇ), a Marxist youth group.
Arrest and trial
On January 11th, 1971, Deniz Gezmiş took part in the robbery of Emek branch of İş Bank/İş Bankasi (TR) in Ankara. On 4 March that year, he kidnapped four U.S. privates from TUSLOG/The United States Logistics Group headquartered in Balgat, Ankara. After releasing the hostages, he and Yusuf Aslan were captured alive between Gemerek-Yeniçubuk, Şarkışla and Sivas following an armed stand-off with law enforcement officers.
Their trial began on July 16th, 1971, after the coup d'état of 12 March. Gezmiş was sentenced to death on 9 October for violating the Turkish Criminal Code's 146th article, which concerns attempts to "overthrow Constitutional order". According to legal procedure at that time, a death sentence had to be endorsed by Parliament before being sent to the President of the Republic for final assent. In March and April 1972 the sentence was placed before Parliament and in both readings the sentence was overwhelmingly approved. Some politicians such as İsmet İnönü and Bülent Ecevit opposed the sentence, but Süleyman Demirel voted in favor of it. He and his colleagues within the AP (Adalet Partisi - Justice Party) gave votes in favor of the executions, shouting, "Three from us, three from them!". - referring to the right-wing Democratic Party politicians (including former Prime Minister Adnan Menderes), who had been executed in 1961 after Yassıada Trials.
On 4 May, President Cevdet Sunay, after officially consulting the Minister of Justice and Prime Minister Nihat Erim, refused to grant Gezmiş a pardon. He was executed by hanging on May 6th, 1972 in Ankara Central Prison along with Hüseyin İnan and Yusuf Aslan.
His last request was to drink tea and listen to Concierto de Aranjuez, Joaquín Rodrigo's guitar concerto.