"In most cases, their arrests have never been officially confirmed and no official has ever said where they are being held or what they are charged with", said the watchdog.
USA intelligence officials reportedly intercepted communications that the Saudis discussed a plan to lure and capture Khashoggi before his disappearance, a person familiar with the situation said in The Post. It's a very serious situation for us and for this White House ...
The Post's report follows Defense Secretary James Mattis's remarks about Khashoggi's disappearance, in which he suggested the U.S. was keeping track of the developments.
Turkish officials say they believe Khashoggi, a critic of Salman who has been living in self-imposed exile in the USA, either was murdered October 2 inside the consulate when he went there to pick up documents to allow him to marry Cengiz, a Turkish national, or was spirited away to Riyadh.
Although it is unclear where their information is coming from, the Turks say after Khashoggi was murdered, his body was dismembered by Saudi officials in the Kingdom's consulate in Istanbul.
Vice President Mike Pence, asked if Washington might dispatch Federal Bureau of Investigation technicians if Saudi Arabia requested it, said, "I think the United States of America stands ready to assist in any way".
Istanbul prosecutors are investigating the incident, while the consulate said on Twitter that it was working in coordination with Turkish authorities.
Khashoggi had been living in self-imposed exile in the USA for the past year.
He told reporters that "nobody knows what happened yet", and expressed a hope that the journalist may still be alive.
"I'm not happy about it", Trump said of Khashoggi's disappearance. Frankly, because it's a reporter, you could say in many respects, it brings it to a level. And he alluded to the sensitivities surrounding the matter, saying he'd prefer not to reveal which Saudi officials he spoke to about it.
Saudi Arabia denies involvement in Khashoggi's disappearance. "I think we'll get to the bottom of it", he added.
She called on Trump to "help shed light" on the journalist's disappearance.
Khashoggi's fiancé Khadija Cengiz has broken her silence over the disappearance of the Saudi critic.
Turkish investigators are looking into two Saudi Gulfstream jets that landed at the airport on 2 October.
The Sabah newspaper, which is close to Turkish President Recep Tayyip Erdogan, published images of what it referred to as the "assassination squad" apparently taken at passport control.
It also shows groups of men arriving and later leaving Istanbul airport, as well as checking-in to a hotel.
The journalist was planning to remarry, and he visited the Saudi Consulate in Istanbul to obtain a document showing that he was legally divorced from his ex-wife. They haven't searched the consulate yet, as they have promised to do. Saudi officials maintain he left the consulate shortly after entering, although it has failed to provide evidence to support that.
"We fear possibly the worst, but at the moment there has been no evidence to suggest otherwise". "It has to prove that Jamal wasn't oppressed at the consulate and that he left safely".