Officials in Turkey say the suspected Reina nightclub gunman, who was arrested overnight, has admitted carrying out the attack.
Istanbul Governor Vasip Sahin says the man, whom he identified as Abdulgadir Masharipov, has admitted his guilt.
Sahin says Masharipov’s fingerprints matched those found at the scene.
There are strong indications he entered Turkey illegally through its eastern borders in January 2016, Sahip added, saying it is clear the attack was carried out on behalf of ISIL.
The state-run news agency Anadolu has identified the man arrested as Abdulgadir Masharipov.
He was detained in the Esenyurt district of Istanbul.
DAILYSABAH (@DailySabah) January 16, 2017
The Hurriyet newspaper says the suspected gunman was arrested in an apartment in a housing complex on the European side of Istanbul at around 11pm local time on Monday.
Media outlets have published photographs of the alleged attacker with a black eye, a cut above his eyebrow and blood on his face and clothing.
A man from Iraq has also been arrested, along with three women from Egypt, Senegal and Somalia.
Are these the only people arrested?
Dozens have been detained in connection with the attack.
Anadolu says other people were detained in raids across the city targeting Uzbek ISIL cells.
What happens now?
Anadolu says the suspect is being questioned at police headquarters in Istanbul.
Has anyone claimed responsibility for the Reina attack?
It has been claimed by ISIL.
The group says it was in revenge for Turkish military involvement in Syria.
What happened in the nightclub?
The attacker shot his way into the packed nightspot on January 1st.
He opened fire with an automatic rifle.
39 people were killed. Dozens were injured.
Turkish citizens as well as nationals from several Arab countries, India and Canada were among those who died.
What they are saying
“Our war with terror and the powers behind it will continue to the end,” – Turkish Deputy Prime Minister Numan Kurtulmus.
“He knew four languages and was well-educated,” – Istanbul Governor Vasip Sahin told a news conference.