A Turkish prosecutor on Wednesday said Saudi journalist Jamal Khashoggi was strangled as soon as he entered the Saudi Consulate in Istanbul as part of a premeditated killing, and his body was dismembered and disposed of.

A statement from chief Istanbul prosecutor Irfan Fidan’s office also said that discussions with Saudi chief prosecutor Saud al-Mojeb have yielded no “concrete results” despite “good-willed efforts” by Turkey to uncover the truth.

The statement is the first public confirmation by a Turkish official that Khashoggi was strangled and dismembered after he entered the Saudi Consulate on October 2 to collect paperwork needed to marry his Turkish fiancee.

Read: 9 key questions Saudi Arabia hasn’t answered about Khashoggi killing

Turkey is seeking the extradition of 18 Saudi suspects detained in Saudi Arabia over the killing of Khashoggi in the Saudi Consulate. It is also pressing Saudi Arabia for information concerning Khashoggi’s remains, which still haven’t been found, as well as who ordered the journalist’s slaying.

Saudi officials have said the kingdom will try the 18 and bring them to justice after the investigation is complete.