The first trial related to Turkey's failed coup started on Tuesday, with 29 police officers facing charges of disobeying orders on the July night rogue soldiers attempted to overthrow the government and killed some 240 people. Since the failed coup, more than 100,000 people have been sacked or suspended in a widespread crackdown targeting the military, police, civil service and private sector. Some 40,000 people have been arrested. Security was tight at the courthouse in Silivri, west of Istanbul, including a heavy police presence. Reporters were not allowed to bring cameras and other equipment into the building. The police officers are charged with disobeying orders to defend President Tayyip Erdogan's palace in Istanbul on the night of the July 15 coup, state-run Anadolu Agency said. Lawyers for the 29 defendants could not immediately be reached to say whether they would deny the charges. During the attempted coup, rogue soldiers commandeered tanks, helicopters and warplanes in Istanbul and Ankara and attacked parliament and other institutions. "Everyone involved in the coup attempt must have a fair trial," Orhan Cagri Bekar, a lawyer who represents some of the victims of the coup, told reporters. "Those who are guilty must be sentenced to the heaviest punishment because this is a betrayal of the country." Prosecutors are seeking three life sentences for 21 of the policemen and sentences of between 7-1/2 to 15 years in prison for the other eight, Anadolu said. While Tuesday's trial is the first related to the coup, it does not include the alleged ringleaders, who are due to go on trial, probably next year, in Ankara. The government said earlier this year that a new court would be built in an Ankara district as there were no courts big enough in Turkey to handle such large numbers of defendants. The government has blamed a US-based Muslim cleric, Fethullah Gulen, for orchestrating the failed coup. Gulen, a former ally of President Erdogan, has denied the charge and condemned the coup.