During the meeting, Ryan expressed The Post's "grave concern" about Khashoggi's disappearance, and said the news organization would view any Saudi government involvement in his disappearance as a flagrant attack on one of its journalists.
Turkish officials say they have concrete evidence Khashoggi was murdered and his body was removed - but they haven't presented it.
Turkish police were looking into two private aircraft which landed at Istanbul's Ataturk airport on Tuesday at different times carrying 15 people of interest in the case, as well as the possibility that Khashoggi was kidnapped and taken aboard one of the planes, local media reported.
Ms Cengiz said she waited outside for 11 hours, but he did not come out.
It is, perhaps, possible that MBS is labouring under a sense of extreme superiority thanks to his connections with the US. "It is [the duty] of the consulate officials", Mr Erdogan said this week.
The mainstream is pointing to Donald Trump's close ties to the 33-year-old Crown Prince, without noting that support for the Saudi regime is longstanding and bipartisan; in 2011 Barack Obama approved $60 billion in arms sales to the kingdom, up to that point the largest weapons transaction in history.
A Turkish official said Saudi Arabia's envoy to Ankara had been summoned to the foreign ministry for a second time on Sunday.
A Washington Post columnist and prominent newspaper editor in Saudi Arabia, Khashoggi mysteriously vanished last week.
Still, Khashoggi's disappearance gives Democrats in particular an opportunity to shine the spotlight on Trump's good rapport with authoritarian leaders.
Consulate officials, however, are not protected from prosecution for "grave crimes" such as murder, and might also be subjected to a civil suit if Khashoggi's family chose to sue.
The timestamped picture has a Turkish caption bearing Mr Khashoggi's name and that he was arriving at the consulate, but the man in shot has his back to the camera.
Turkish President Recep Tayyip Erdogan, left, chats with Hungarian President Janos Ader as he steps out on the terrace of the presidential Alexander Palace in Budapest, Hungary, Oct. 8, 2018. "We have some concrete information, it won't be an unresolved crime", the Middle East Eye reported. "God willing, we will not be faced with a situation we do not want". The first reports out of Turkey were that he exited the Consulate and then disappeared.
Government sources said police believe the journalist was killed inside the consulate.
"We call on the government of Saudi Arabia to support a thorough investigation of Mr. Khashoggi's disappearance and to be transparent about the results of that investigation", Pompeo said in a statement.
"That is effectively terminating consular relations between Saudi Arabia on Turkish territory", Professor Saul said.
Turkey's Foreign Ministry said a search would be conducted there. Saudi officials have said that he left shortly afterwards but his fiancée, who was waiting outside, said he never appeared.
Meanwhile, the United Nations human rights office urged both countries to investigate the case.
A senior Turkish police source told Middle East Eye that police believed that Khashoggi was "brutally tortured, killed and cut into pieces" inside the consulate after visiting the building on October 2. Turkish officials are trying to identify them as part of their probe into Khashoggi's disappearance.