A Turkish court on Saturday ordered the formal arrest of an Uzbek man suspected of killing 39 people on New Year's night at an Istanbul nightclub, local news agency reported.
In a massive operation in January, Turkish authorities detained Abdulgadir Masharipov, 34, who spent 17 days on the run following the attack, claimed by Islamic State (IS) militants.
The private Dogan news agency reported that the suspect was formally arrested after being taken to an Istanbul court.
Masharipov had been detained on January 17. It is not exceptional in Turkey for a formal arrest -- an important procedural step in legal proceedings -- to take place weeks later, especially for cases involving major crimes.
He is facing several charges from "attempting to destory constitutional order," "membership of an armed terrorist organisation," to "murdering more than one person", the state-run Anadolu news agency reported.
Turkish authorities said Masharipov trained in Afghanistan, adding that he confessed to carrying out the attack during the testimony.
Masharipv is believed to have first entered Turkey in January 2016.
Of the 39 killed in the Reina attack, 27 were foreigners including citizens from Lebanon, Saudi Arabia, Israel, Iraq and Morocco who had gone to the club to celebrate New Year.
The attack, just 75 minutes into 2017, shook Turkey which had already been hit by a series of attacks in 2016 blamed on Islamist and Kurdish militants that has left hundreds dead.