Speaking at a memorial in London on Monday, Hatice Cengiz expressed disappointment in the "leadership of many countries."
Singling out Trump, she urged him to "help reveal the truth and ensure justice be served." "He should not pave the way for a cover-up of my fiance's murder. Let's not let money taint our conscience and compromise our values," she said.
Cengiz also told the memorial that she wishes she had entered the consulate instead of her fiance.
She said in reference to an alleged Saudi hit squad sent to kill the Washington Post Journalist: "If only I knew that would be the last time I would see my Jamal, his smile, hear his laughter, I would have stood in front of that murderous team myself."
Saudi Arabia's top prosecutor, Saud al-Mojeb, arrived at Istanbul's main courthouse Tuesday for more talks with Istanbul's chief public prosecutor, Irfan Fidan, on the investigation into the killing, Turkey's state-run Anadolu Agency reported.
The two had met for an hour and 15 minutes on Monday as part of an agreement between Riyadh and Ankara for cooperation over the investigation.
Turkey is seeking the extradition of 18 Saudi suspects detained in Saudi Arabia for the Oct. 2 killing of Khashoggi — a journalist who had written critically of Saudi Arabia's crown prince in columns for The Washington Post.
It is also seeking Saudi Arabia's help to locate Khashoggi's body, which still has not been found.
Saudi Foreign Minister Adel al-Jubeir has said the kingdom will try the perpetrators and bring them to justice after the investigation is completed.
Under mounting international pressure, Saudi Arabia has changed its narrative about Khashoggi's killing several times, and has recently acknowledging that Turkish evidence shows it was premeditated.