A Turkish court in capital Ankara handed down aggravated life sentences to 18 members of the Fetullah Terrorist Organization (FETÖ), said a judicial source Monday.
The court said they were guilty of martyring senior staff sergeant Omer Halisdemir during the 2016 defeated coup bid in Turkey.
They were sentenced on the counts of intentional murder and attempt to overthrow the constitutional order.
Later during the day, the sentences of 13 convicts were reduced to life sentences through discretionary mitigation, the source added.
Halisdemir -- who was martyred during the defeated coup attempt night after he shot dead a senior coup plotter -- became a symbol of the Turkish nation's resistance against the defeated coup.
Halisdemir shot pro-coup Brig. Gen. Semih Terzi in the head after the latter attempted to seize control of the Special Forces Command in capital Ankara. Pro-coup soldiers later martyred Halisdemir.
According to the government, FETÖ and its U.S.-based leader Fetullah Gulen orchestrated the defeated coup on July 15, 2016, which left 251 people martyred and nearly 2,200 injured.
Ankara also accuses FETÖ of being behind a long-running campaign to overthrow the state through the infiltration of Turkish institutions, particularly the military, police, and judiciary.