ISTANBUL, Turkey -- Twenty-nine Turkish former police officers went on trial in Istanbul on Tuesday accused of aiding the failed military coup in July - the first trial over the attempt that led to some 270 deaths.

Renegade officers in Turkey’s military used tanks, fighter jets and helicopters in their July 15 attempt to unseat the government, attacking the parliament and other key buildings. Turkey blamed it on a network of followers of the U.S.-based Muslim cleric Fethullah Gulen - an ally turned foe of President Recep Tayyip Erdogan.

Gulen, whom Turkey wants extradited from the United States so that he may also face trial, has denied any involvement in the coup.

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The government declared a state of emergency following the coup and has launched a large-scale crackdown against Gulen’s movement, which it has declared a terror organization. More than 40,000 people have been arrested for alleged involvement in the coup while tens of thousands of other suspected Gulen followers have been purged from government jobs.

The police officers standing trial in a prison and courthouse complex in the outskirts of Istanbul include three police helicopter pilots. They are accused of aiding the coup by not carrying out their duties, including disobeying orders to protect Erdogan’s Istanbul residence on the night of the coup, according to the state-run Anadolu Agency.

Prosecutors have demanded aggravated life prison terms for 21 officers charged with “attempted coup” while eight others face maximum 15 years in prison for membership in a terrorist organization.

The court was scheduled to hear the suspects’ statements in their defense on Tuesday and Wednesday.