Turkey's leading television channels showed video footage of Samast posing in front of a Turkish flag and also holding anther flag next to security officials dressed in para-military and regular police uniforms shortly after his arrest on January 21.
"The pictures were shown on television in the evening [Thursday] and inspectors will clarify who took the pictures and why. We in the police will do everything necessary," Ismail Caliskan, a police spokesman, said.
The Gendarmerie, Turkey's paramilitary police, denied reports the footage was shot at one of their offices in Samsun, the city where Samast was arrested after a nationwide manhunt.
Dink, 52, had been a hate figure for ultra-nationalists because of his comments on the mass killing of Armenians on Turkish soil in 1915, still a highly sensitive issue in this European Union candidate country.
Tayyip Erdogan, Turkey's prime minister, has already questioned whether the killing was the work of Turkey's so-called "deep state" - code for shadowy ultra-nationalist elements in the security forces ready, if need be, to act outside the law.
"What appears on the video is in itself not new for Turkey. The difference is that this time the media decided to publish it," Semih Idiz, the diplomatic editor for CNN Turk, said.
"The implications of this scandal are enormous. It's too early to tell whether ministers will be fired."
Eight people, at least seven of them from the Black Sea province of Trabzon, have been charged over the murder.
Authorities have been accused of failing to act on warnings that ultra-nationalists planned to murder Dink. Opposition parties have demanded the resignation of the interior minister.
Last week, the interior ministry dismissed the police chief and governor of Trabzon and sent prosecutors to investigate whether local authorities were at fault.
Ismet Berkan, editor-in-chief of the Liberal newspaper Radikal, said the release of the video images was like killing Dink a second time. He said it showed extreme nationalism in Turkey was again on the rise.
Pressure is mounting on the government to crack down on ultra-nationalist groups, a tricky task in a year of presidential and parliamentary elections.