Many ethnic Kurds and Turks hope that an ongoing investigation into an undercover organization may help explain hundreds of unsolved murders, disappearances and bombings which rocked Turkey in the early 1990s.
State prosecutors allege that a highly-secretive group - 'Ergenekon' - was responsible for many unsolved, high-profile killings in Turkey in recent years.
These include the murders of leading journalists, such as Hrant Dink, assassinated in January 2007, and Ugur Mumcu, killed in 1993.
Prosecutors also allege that the group was behind plans to destabilize Turkey and pave the way for a military coup to unseat the current government. Some 86 people have so far been detained in the case, including media, political and retired military figures.
"The Ergenekon case is very, very important," Hasan Fendoglu, an advisor to Recip Tayyip Erdogan, the former prime minister, told Al Jazeera.
"It is the first case of its kind in the Republic of Turkey in 40 years. If we can solve this case, we will have made some major progress in human rights," Fendoglu, who also heads the Human Rights Presidency, the official human rights body, added.
But there are fears that political pressures may derail what many are calling the most important Turkish criminal investigation in years.
While many of the high-profile assassinations happened in Istanbul and Ankara, most of Turkey's unsolved murders and disappearances of the last two decades have centered in the country's troubled southeast.
This region has an ethnic Kurdish majority and has been the scene of continuing conflict between Turkish security forces and fighters of the Kurdish Workers Party (PKK), who have led a violent campaign for independence. More than 30,000 people have been killed in this conflict so far.
Interest in Ergenekon is therefore high in the southeast and in Diyarbakir, its regional capital. Many are hoping that the case will help solve decades-old murders and disappearances.
One such unsolved disappearance concerns Mecit Gundem, a farmer from the ethnic Kurdish village of Hazro.
He has not seen his father since 1991.
"The jandarma [paramilitary rural police gendarme force] came to our village at 4am," he told Al Jazeera.
"They came to our house and took away my father, Ibrahim, right in front of many witnesses. But when we went to the jandarma station later that morning and asked for him, they told us he wasn’t there."
Since that day, no one has heard anything of Ibrahim. "We kept asking, but they just told us they didn’t know anything about him, or whether he was dead or alive," Mecit said.
But the Ergenekon case may have offered a fresh clue.
"One day a few weeks ago, there was an article in a newspaper that caught my eye," he says.
"It said that according to a file that had come to light because of the Ergenekon investigation, there was a death squad operating in my region back in the 1990s."
"The file said that this squad had operated on the instructions of a secret group within the state, which ordered it to kill anyone they suspected of involvement with the PKK. It said too that this group killed a man from Hazro the same day my father disappeared, along with many others from other places."
Mecit is now pushing local human rights lawyers to take up the case again.
One such lawyer is Muharrem Erbey, chair of the Diyarbakir branch of Turkey’s Human Rights Association (IHD).
"Ergenekon is extremely important for Kurdish society," he says.
"Why?" He points to a row of five portraits on the wall of his office.
"They are all human rights activists killed by Ergenekon. We have lost many, many people over the years to them."
The IHD in Diyarbakir also has files on some 1,285 people who were allegedly arrested by the police, the jandarma, the army and other security forces since 1991 – and were never seen or heard from again.
"The state used groups like Ergenekon to kill Kurdish activists, intellectuals and businessmen," he says. "The group became very strong as the conflict intensified. Ergenekon grew out of the Kurdish issue."
The "deep state"
Some analysts see Ergenekon as just one part of the 'deep state' – a shadowy network of groups responsible for many killings and disappearances over the years.
"The heyday of the deep state was the 1990s, when it was vastly powerful," says Gareth Jenkins, Turkey analyst with the Washington-based Jamestown Foundation.
"The deep state was never a single, structured organization, but a web of groups and networks, some of which were autonomous, others of which sometimes cooperated with each other. The unifying factor was not central control but shared immunity from prosecution."
Others dispute any official culpability though. "Our police stations and security services have all been doing their work properly here," Cemal Husnu Kansiz, the deputy governor of Diyarbakir, told Al Jazeera.
"If there are any specific cases of disappearances or killings then they always follow them up. In this instance, there are no specific human rights problems in Diyarbakir."
This is not a widely-held view in the region, however. Tahir Elci, a local lawyer, recalls another case he was involved in, this time from 2001.
"Two local politicians in Silopi [a nearby town] from the pro-Kurdish party, HADEP, were called to the local jandarma station in the middle of the day," he says.
"They went there by car and were never seen again. We asked after them, and the jandarma said, 'yes, they came, then left, we don't know what happened'.
"We took the case all the way to the European Court of Human Rights, who ruled in our favor – that Turkey had failed in its responsibilities towards the two men. We still haven't found them. The jandarma commander in the area at the time, Levent Ersoz, refused to testify."
Ersoz has also now been indicted by state prosecutors in the Ergenekon case, charged with being a key member of the group. A warrant for his arrest was issued on August 14, when his whereabouts were unknown.
The jandarma would not comment on any of these cases.
"On Ergenekon, we cannot comment on an ongoing case – we will just have to wait and see," Kansiz told Al Jazeera.
Many hope though that the Ergenekon case will reveal more connections to the disappeared of the southeast, as well as to cases in other parts of Turkey.
Yet there are also concerns that the Ergenekon file may be politically motivated and badly put together.
"All the people who have been accused so far are also known for their anti-government stance," says Onur Oymen, spokesman for the Republican People's Party, Turkey's main parliamentary opposition.
"In the indictment, sometimes you also find the same person mentioned as a member of Ergenekon and then later mentioned as someone Ergenekon wanted to kill."
At the same time, others worry about the ability of the judiciary to successfully investigate and prosecute such cases.
"One of the issues is how will the justice system deal with Ergenekon when there are major question marks over the judiciary and the pressure – political pressure – that can be brought to bear on it," says Emma Sinclair-Webb of the international group, Human Rights Watch.
Yet officials remain confident.
"It is impossible for political pressure to be brought to bear in this," says Fendoglu. "The courts are completely independent of the government."
Meanwhile, Mecit has a simple request.
"I just want to know what happened to my father. I want to know where and how he was killed. My whole family just wants to know."
Istanbul chief prosecutor Aykut Cengiz Engin speaks to the media about the "Ergenekon" network at a court in Istanbul on July 14, 2008.