President Recep Tayyip Erdogan's suggestion that Turkey might reinstate the death penalty to punish those involved in last week's failed coup bid has alarmed European leaders. Turkey completely abolished the death penalty in 2004 as part of its efforts to join the European Union, which makes its removal an non-negotiable pre-condition for membership. No judicial executions have taken place in the country since left-wing militant Hidir Aslan was hanged on Oct. 25, 1984 in the wake of the 1980 military coup. But might capital punishment be on the way back? The death penalty was used with relative frequency for serious crimes after the foundation of modern Turkey in 1923. But its most notorious use came after the military coup of 1960 which resulted in the rounding-up of members of the government. Then prime minister Adnan Menderes, foreign minister Fatin Rustu Zorlu and finance minister Hasan Polatkan were all executed on the prison island of Imrali in September 1961. Erdogan frequently invokes the execution of Menderes, one of his political heroes, as an example of injustice. In 1972, young leftist activists Deniz Gezmis, Yusuf Aslan and Huseyin Inan were executed in 1972. They remain heroes for the Turkish socialist movement to this day. Another wave of executions followed the 1980 coup. Levon Ekmekjian, a Lebanese Armenian, was executed in 1983 in Ankara after being found guilty of carrying out a deadly assault on the capital's international airport on behalf of an Armenian militant group. Parliament voted to abolish the death penalty during peace time in 2002, with full abolition for all crimes following in 2004. But even before the abolition, it had observed a de-facto moratorium since the 1980s. The abolition led the 1999 death sentence against to Kurdish separatist leader Abdullah Ocalan — and those of all others on death row — to be commuted to life behind bars. Ocalan had appealed his sentence at the European Court of Human Rights. He remains behind bars in Imrali, an island in the Sea of Marmara off Istanbul. In 1991, all death sentences handed down in Turkey before April of that year were commuted to between 10 and 20 years in jail, depending on the nature of their crimes, according to Amnesty International. Erdogan has stressed any decision to reinstate capital punishment would have to come from parliament. But he has said he would approve any decision the legislature took on the matter. Thousands of Erdogan's supporters have taken to the streets in recent days to condemn the coup plotters and loudly backed calls for the reinstatement of capital punishment. This is not the first time in recent years that there has been popular pressure for capital punishment to return. The attempted rape and brutal murder of Ozgecan Aslan in 2015 prompted calls, including from cabinet ministers, for the death penalty for the three men found guilty. In 2012, Erdogan, at the time prime minister, also hinted at its reinstatement, again due to popular support, to deal with cases of terrorism. Opponents denounced it as a political tactic.