The camera never leaves the man's unsmiling face as he walks through Taksim square, one of Istanbul's prime tourist spots, during the 44-second video broadcast on state-run Anadolu television and other media.
It wasn't immediately clear if it was filmed before or after the New Year's massacre at the Reina nightclub, or how the footage was obtained. The gunman, who hasn't been publicly identified, is still at large.
The Islamic State group claimed the attack on Monday, saying a "soldier of the caliphate" had carried out the mass shooting to avenge Turkish military operations against IS in northern Syria.
Layan Nasser, an 18-year-old Arab Israeli dental assistant who had traveled to Istanbul to celebrate the New Year with friends, was among the dead. Thousands attended the teen's funeral on Tuesday in the Israeli city of Tira.
"She had dreams to work, to progress, to study, to raise a family, but unfortunately the terror put an end to her dreams," Tira mayor Mamoun Abd El Hai said.
At least 14 people have been detained in connection with the attack. Two foreigners were detained at Ataturk airport's international terminal on Tuesday after police checked their cell phones and luggage, according to Anadolu.
Hurriyet newspaper said that a woman identified by Turkish media as the wife of the massacre suspect has told police she didn't know her husband was an IS member.
The woman was detained in the central town of Konya as part of the investigation. Neither she nor her husband has been identified by name. Hurriyet said on its online edition Tuesday that the woman said she learned about the attack on television and told police she didn't know her husband harbored "sympathies toward" IS.
Media reports say the gunman flew to Istanbul from Kyrgyzstan with his wife and children on Nov. 20. From there, they drove to the Turkish capital, Ankara, before arriving in Konya on Nov. 22.
The family rented a studio in Konya, paying three months of rent upfront. The gunman told the real estate agent he had arrived in Konya in search of work, according to the report.
Hurriyet said the gunman returned to Istanbul Dec. 29.
Several media outlets on Monday, citing unnamed security sources, said the man was believed to be from Central Asia and may have been part of the cell that staged a June attack on Istanbul's Ataturk Airport that killed 45 people.
Haber Turk newspaper on Tuesday said the man is thought to be a member of China's Muslim Uighur minority. A Kyrgyz passport circulated on Turkish media but police said it did not belong to the gunman.
The nightclub assailant, armed with a long-barreled weapon, killed a policeman and a civilian in the early hours of 2017 outside the club before opening fire on the estimated 600 people inside. The establishment is frequented by famous locals, including singers, actors and athletes. Most of the dead on Sunday were foreign tourists.
Turkey has been rocked by violence in the past year, carried out by IS as well as by Kurdish militants. The government survived a failed coup over the summer and is fighting against Kurdish insurgents. Parliament votes Tuesday on whether to extend the state of emergency declared after the coup attempt.
The country launched an offensive to northern Syria in August in hopes of clearing a strategic border area of IS militants and stemming the gains of Kurdish fighters. Turkish jets regularly bomb IS targets in the Syrian town of al-Bab in support of Syrian opposition forces try to re-capture it from the extremists.
Turkey's interior minister told parliament Tuesday that authorities thwarted a total of 339 possible attacks in 2016, including 313 planned attempts by the outlawed Kurdistan Workers' Party, or PKK, and 22 by the Islamic State group.
Associated Press writers Suzan Fraser in Ankara, and Lori Hinnant in Paris, contributed to this report.
Copyright 2017 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.