The main suspect in the murder of Turkish-Armenian journalist Hrant Dink has been arrested, Turkish Prime Minister Recep Tayyip Erdogan has said.
Samast was caught on film near the scene of the killing
The governor of Istanbul said police captured Ogun Samast, aged 16 or 17, on a bus in the Black Sea city of Samsun.
Mr Samast was earlier named as the suspect pictured in security camera images near the scene of the killing.
Mr Dink, 53, was shot dead in broad daylight outside his newspaper offices in Istanbul on Friday.
He was well-known for writing controversial articles about the mass killing of Armenians by Turks during World War I.
Istanbul governor Muammer Guler announced the details of the capture in a live television broadcast.
He said Mr Samast had been detained at Samsun bus station while apparently returning to his hometown of Trabzon from Istanbul.
Hrant Dink was one of Turkey's most prominent Armenian voices
The governor added that Mr Samast was carrying a gun at the time, and that six other suspects had been detained in Trabzon.
All seven will be brought to Istanbul for questioning on Sunday and police are investigating whether they were part of a group, Mr Guler said.
The governor emphasised that Ogun Samast - who he said was born in 1990 - had been detained after 32 hours.
The suspect was identified by his own father when he saw television images taken at the scene of Friday's killing.
A clear image taken from security camera footage showed a man apparently running from the scene, tucking what officials said was a gun into his belt.
Dink's secretary told investigators Mr Samast had asked to meet Mr Dink earlier on Friday, before the killing, Mr Guler said.
After the request was turned down, the secretary saw Mr Samast waiting on the street outside Mr Dink's office, he said.
Three suspects detained in Istanbul on Friday shortly after the killing have been released.
Mr Dink's murder shocked Turkey and Prime Minister Erdogan vowed repeatedly that his killer would be caught.
Journalists and politicians in Turkey have expressed outrage at the killing, which many described as a political assassination, while the US, EU, France, and several human rights groups also voiced shock and condemnation.
Mr Dink had received multiple death threats from nationalists because of his views on the mass killings of Armenians during the final days of the Ottoman Empire.
He was convicted in October 2005 for writing about the Armenian "genocide" in 1915, a claim denied by the authorities in Ankara.
The issue is a sensitive subject in both Armenia and Turkey. Many Armenians have campaigned for the killings to be recognised internationally as genocide.
The Armenian government condemned Mr Dink's murder.
Its president, Robert Kocharian, said the killing "raises numerous questions and deserves the strongest condemnation".
The speaker of Armenia's parliament, Tigran Torosyan went even further.
"Following the murder, Turkey should not even dream about joining the European Union," the Armenian news agency Arminfo quoted him as saying.
The two countries still have no official relations since Armenia gained independence after the break up of the Soviet Union in 1991.