Hurriyet and Karar newspaper reports Monday cited unnamed security officials saying that authorities have determined that the gunman who killed 39 people comes from a Central Asian nation and is believed to be either from Uzbekistan or Kyrgyzstan.
Police had also established similarities with the high-casualty attack at Ataturk Airport in June and was investigating whether the same IS cell carried out both attacks.
The gunman, who is still at large, killed a policeman and another man outside the Reina club in the early hours of 2017 before firing at people partying inside.
Nearly two-thirds of the dead were foreigners, many from the Middle East.