"Yet there are other, no less significant questions whose answers will contribute to our understanding of this deplorable act", said Erdogan, including the whereabouts of Khashoggi's body, the identity of the "local collaborator" who was given his remains, and who ordered the killing.
"I really don't know how to express myself", she said.
Erdogan has called for the 18 suspects - including the alleged 15-man hit team who travelled to Istanbul and left the same day - to be extradited for trial in Turkey.
Istanbul's chief prosecutor says Khashoggi was strangled immediately after he entered the Saudi consulate in Istanbul, Turkey, on October 2 and that his body was dismembered and removed from the consulate.
A Turkish prosecutor said on Wednesday that Khashoggi was strangled and dismembered soon after he walked into the Saudi consulate. Saudi Arabia since then announced a full investigation into the killing. Claims that Khashoggi had died in a fight followed - and last week, a Saudi prosecutor said the killing was premeditated.
Yesterday both the "Post" and the "New York Times" cited White House officials as saying Prince Mohammed called officials close to President Donald Trump to smear Mr Khashoggi as a unsafe Islamist.
"According to the latest information we have, the reason they dismembered his body is to dissolve it easier", he said.
Rep. Gerry Connolly, D-Va., speaks at an event to remember Jamal Khashoggi in Washington.More news: Trump Sends 5,200 Troops To Mexico Border As Caravan Advances
Khashoggi's death, which reportedly happened in the Saudi Arabian consulate in Turkey, has enraged several individuals, institutions and countries globally.
The case has provoked worldwide condemnation, but one month after Khashoggi was killed, the joint Turkish and Saudi probe has made little progress and many questions remain unanswered.
Turkey's justice minister has meanwhile renewed a call for Saudi Arabia to cooperate in the investigation into the killing, saying "no one can escape responsibility".
Omer Celik, the spokesman for Erdogan's ruling AK Party, said on Friday legal action would be taken against Kilicdaroglu over the comments.
The murder, initially covered up by Saudi officials, caused a diplomatic crisis between Saudi Arabia and its allies.
Erdogan wrote: "As responsible members of the worldwide community, we must reveal the identities of the puppet masters behind Khashoggi's killing and discover those in whom Saudi officials -still trying to cover up the murder - have placed their trust".
We therefore respectfully call on you to immediately authorize an independent, worldwide investigation into the murder of Jamal Khashoggi that would lay the groundwork for identifying and holding accountable the perpetrators of this grievous crime. But the Trump administration has taken a position that is devoid of moral foundation.