The Turkish authorities have released CCTV images of a man suspected of involvement in the death of a prominent journalist of Armenian descent.
Police believe the man is tucking a gun into his trousers
In one image the young man can be seen running while tucking what officials believe is a gun into his belt.
Hrant Dink was shot dead near his newspaper's Istanbul offices on Friday, sparking angry protests.
He had written extensively about the massacre of Armenians during the final days of the Ottoman Empire in 1915.
The photographs released by Istanbul's governor Muammer Guler came from a security camera on the street where Mr Dink died after being shot twice.
The images have been enhanced by investigators in order to help with identification, officials said, and the police have set up a phone line for members of the public to pass on information.
The suspect appears to be in his late teens or early 20s. Of slim build, he is casually dressed in jeans, a denim jacket and white knitted hat and has a thin moustache.
In one image he is seen walking normally, in another he is running, with his hands near his waist - officials believe he is hiding a gun.
Many in Turkey think that Dink was targeted for his controversial writing on the killings of hundreds of thousands of Armenians by the Ottoman Turks nine decades ago.
The issue is a sensitive subject in both Armenia and Turkey. Many Armenians have campaigned for the killings to be recognised internationally as genocide.
Turkey denies any genocide, saying the deaths were a part of World War I.
Dink was found guilty in October 2005 of insulting Turkish identity after he wrote an article which addressed the mass killings.
Hrant Dink was one of Turkey's most prominent Armenian voices
Dink was one of Turkey's most prominent Armenian voices and despite threats on his life, he refused to stay silent.
Even with the known tensions surrounding Dink's work he was not provided with a bodyguard, sparking criticism that not enough had been done by the authorities to protect him.
But Mr Guler says that this was because Dink had not asked for any extra security effort.
"Because he didn't request protection, he didn't get close protection," Mr Guler said. "Only general security precautions were taken."
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.
The Armenian government has condemned the murder with President Robert Kocharian saying: "The killing of this well-known Armenian journalist in Turkey raises numerous questions and deserves the strongest condemnation.
"We hope that the Turkish authorities will do everything possible to find and punish the culprit strictly in accordance with the law".
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.