President Recep Tayyip Erdoğan held a phone call with his U.S. counterpart Donald Trump over Saudi journalist Jamal Khashoggi's murder, investigations in the U.S. into the Gülenist Terror Group (FETÖ), the anti-terror fight in Syria and bilateral relations, the Turkish presidency said in a statement late Friday.

The presidents agreed that all aspects of Khashoggi's killing must be uncovered and the case should not be covered up.

Khashoggi, a frequent contributor to The Washington Post, was killed Oct. 2 inside the Saudi Consulate in Istanbul. His body has yet to be returned to his family amid reports that it was chemically dissolved.

In their phone call, Erdoğan and Trump also stressed the importance of closer cooperation between Ankara and Washington in the fight against all terror groups.

The two leaders also discussed bilateral ties, ongoing legal cases in the United States and developments in Syria, the presidency said, adding that they had discussed the rapid completion of a roadmap in Syria's Manbij.

Erdoğan also conveyed to Trump Turkey's expectation for the U.S. to end its support for the PKK's Syrian affiliate, People People's Protection Units (YPG), an issue that has long infuriated Ankara and strained ties between the NATO allies.

The U.S. has been militarily supporting and cooperating with the Syrian Democratic Forces (SDF), which is an umbrella group consists mostly of YPG terrorists, under the pretext of fighting against Daesh terror group. This support remains as a source of tension between Washington and its NATO ally Ankara, which has been suffering from the PKK's decades-old deadly campaign against the state.

The PKK is listed as a terrorist organization by Turkey, the U.S. and the European Union. The PYD and its armed branch the YPG are the PKK's Syrian affiliates.