By Jonathan Head
BBC News, Istanbul
The case began with revelations from Ozden Ornek's laptop
The charges filed against 20 senior military officers in Turkey this week mark the most serious development to date in a series of alleged plots against the government by members of the armed forces.
It all started with Nokta ("Point"), a small weekly news magazine.
In its edition published on 29 March 2007, it ran details of diaries found on the laptop computer of retired Admiral Ozden Ornek, former commander of the Turkish Navy.
In them the admiral allegedly wrote of various action plans, which he purportedly discussed with many of his military colleagues, intended to undermine the government led by Recep Tayyip Erdogan and his Islamist-rooted Justice and Development Party (AKP).
Shortly after this, Nokta's offices were raided by the police at the request of a military prosecutor, and the magazine was closed down, never to reopen.
Three months later a large quantity of grenades and explosives were discovered by police hidden in the roof of a house in Istanbul.
Over the following months, these two cases were tied by state prosecutors into a much larger conspiracy they called Ergenekon.
Around 200 people, including some senior military personnel, were charged with being members of a massive terrorist conspiracy in three indictments that ran to a total of 4,364 pages.
The first trials began in began in October 2008.
But after the initial drama of military men being brought before civilian courts on such spectacular charges, the Ergenekon investigations have become bogged down.
HOW 'COUP PLOTS' EMERGED
June 2007: Cache of explosives discovered; ex-soldiers detained
July 2008: 20 arrested, including two ex-generals and a senior journalist, for "planning political disturbances and trying to organise a coup"
July 2008: Governing AK Party narrowly escapes court ban
October 2008: 86 go on trial charged with "Ergenekon" coup plot
July 2009: 56 in dock as second trial opens
Jan 2010: Taraf newspaper reports 2003 "Sledgehammer" plot to provoke coup
Feb 2010: More than 40 officers arrested over "Sledgehammer"; 20 charged
Dozens of hearings have produced little hard evidence of a conspiracy.
The indictments are sometimes contradictory and contain very sweeping allegations.
And they are based on testimony from some decidedly questionable sources.
Sceptics have accused the government of exploiting Ergenekon to intimidate its opponents.
So are these latest charges against Turkish military personnel just more of the same?
Like Ergenekon, Operation Sledgehammer has come to light through documents leaked to the media - in this case an entire suitcase-full, given to the campaigning newspaper Taraf.
But these give details of a much more specific plot.
Dated from November 2002, shortly after the AKP won its first, landslide election victory, they include proposals for a number of actions intended to create the conditions for military intervention, including bombing two mosques in Istanbul and "arranging" for a Turkish air force jet to be shot down in a clash with Greece - all to create the conditions for military intervention.
The documents list names, ranks and serial numbers of all the military personnel tasked with carrying out the actions, as well as listing details of thousands of bureaucrats and journalists likely to be either sympathetic or hostile to a military takeover.
They are approved by a signature alleged to be that of the then commander of the First Army region, General Cetin Dogan.
Recent accusations have been leaked to Taraf
The number, and seniority, of the military suspects in this case is unprecedented.
If prosecutors can show that the documents are genuine, and can link them to a seminar in March 2003 attended by much of the military top brass, details of which have also been leaked to Taraf, the once unimpeachable prestige of the armed forces would suffer far worse damage than it has from Ergenekon.
But the deep political polarisation in Turkish society will inevitably colour how people respond to these most recent allegations.
The military's long history of coups and dirty tricks will persuade many to believe the accusations.
Yet the way they came to light - leaked, like so many other plots, to a single newspaper, their origin unknown - will persuade others that they are intended to discredit the armed forces, seen by many as the last defence of Turkey's secular way of life.
Certainly questions hang over the judiciary's ability to bring these investigations to a credible conclusion.
The draconian punishments meted out by judges here for light offences have already led the European Union to demand wholesale reform of the criminal justice system.
Verdicts reached by Turkey's highest courts are often viewed as overtly political, and it is no secret that the judiciary is as riven by competing political allegiances as the rest of the country.