Turkish sources have told media outlets they believe the Saudi writer and critic was killed inside the consulate in what they described as "premeditated murder".
Saudi officials have countered that claim, insisting Khashoggi left the building before vanishing.
Here are the latest developments:
Thursday, October 18
US Treasury Secretary withdraws from Saudi conference. Secretary of US Treasury, Steven Mnuchin, says he will not attend next week's investment conference in Saudi Arabia.
US gives Saudi Arabia 'few more days' on Khashoggi
US Secretary of State Mike Pompeo says he told President Donald Trump that the US should give Saudi Arabia a few more days to wrap up its investigation into Khashoggi's disappearance.
"I told President Trump this morning that we ought to give them a few more days ... so that we too have a complete understanding of the facts" before deciding on a response, Pompeo told reporters at the White House.
Putin wants more evidence on Khashoggi's fate
Vladimir Putin says Russia would wait for the outcome of an investigation into Khashoggi's disappearance before deciding what impact the writer's fate may have on relations with Saudi Arabia.
Speaking at an international policy forum in Sochi, the Russian president called Khashoggi's disappearance a "tragedy", but said Moscow needs "to understand what happened" before deciding what impact it may have on ties with Riyadh.
"Those who believe that there was a murder must present evidence," he said.
Joe Biden: Trump 'seems to have a love affair with autocrats'
A former US Vice President has criticised Trump's response to Khashoggi's disappearance, saying the president "coddles" dictators.
Joe Biden told CBS' "This Morning" programme that if Saudi Arabia is found to be responsible for the journalist's suspected murder, the kingdom should "absolutely, positively" face consequences.
Biden, who has been tipped as a potential Democratic presidential candidate for the 2020 elections, said the "retaliation" could take the form of cancelled arms sales.
He added that his doubts about Crown Prince Mohammed leadership have "been confirmed".
"My doubts are that there's very little of rule of law, respect for human rights, dignity and the allegations that are made so far - we don't know yet - are not inconsistent with the way the kingdom would act and so I'm very worried that the president seems to have a love affair with autocrats and the idea that he's already making excuses before the facts are known is typical but it hurts us internationally," he said.
UK trade minister pulls out of Saudi conference
British trade minister Liam Fox has pulled out of the Saudi investment summit, saying the time "was not right for him" to attend the Future Investment Initiative in Riyadh on October 23.
"The UK remains very concerned about Jamal Khashoggi's disappearance," a spokesperson for the minister said. "Those bearing responsibility for his disappearance must be held to account."
Turkish officials: Audio reveals Khashoggi was beaten as he entered the consulate
Sources in the Turkish police and public prosecutor's office have told Al Jazeera that an 11-minute audio recording reveals Khashoggi was beaten up as he entered the Saudi consulate.
The recording purportedly features voices in the A and B blocks of the consulate building, which are part of the building's entrance.
The information comes a day after Turkish authorities searched the Saudi consulate and the residence of the consul general.
Fingerprints found during the search include those of Salah Muhammad al-Tubaigy, an autopsy expert from Naif Arab University for Security Sciences.
He is among the 15 men suspected of forming a Saudi hit squad to kill Khashoggi. His fingerprints were found around an electrical socket in the consulate.
None of the men entered Turkey on fake passports, according to sources in the public prosecutor's office, who say some are thought to have used diplomatic passports.
Sources have also told Al Jazeera that an individual close to Khashoggi is believed to have been relaying information back to Saudi Arabia about the journalist's actions and whereabouts since he left the kingdom.
Dutch cancel Saudi trade mission
The Dutch government cancelled a trade mission to Saudi Arabia next month due to concerns over the disappearance of Khashoggi, a spokeswoman said.
"All trade missions to the country have been suspended for now," a spokeswoman for PSPS Consultants, which had organised the trip for the government told Reuters.
The decision came minutes after Finance Minister Wopke Hoekstra said he was scrapping plans to attend the Future Investment Initiatives conference in Riyadh next week.
Also on Thursday, the CEO of French defence electronics group Thales announced that he would no longer be attending the conference, however the company will still be represented by Jean-Loic Galle, an executive in Thales' space division.
Searches turn up fingerprints and other "important" samples
Turkish sources have told Al Jazeera that "important samples" were found during searches of two Saudi diplomatic buildings in Istanbul on Wednesday.
Al Jazeera's Charles Stratford, reporting from Istanbul, said particular attention had been paid to an area of the consulate called the "C-block".
"It was only open to diplomatic staff. Sources in the last couple of hours have said that they have very strong evidence that Khashoggi was killed inside the C-block of the consulate.
Sources told Al Jazeera that they found fingerprints inside C-block of six of the 15 men accused of forming part of a hit-squad.
Investigators spent more than 12 hours scouring the consulate and consul general's residence for clues about Khashoggi's fate. French economy minister pulls out of Saudi conference
French Economy Minister Bruno Le Maire has become the latest high profile figure to drop out of an economic conference in Saudi Arabia over the alleged murder of Khashoggi.
"I won't go to Riyadh next week," he told France's Public Senate TV channel on Thursday, saying the journalist's disappearance was "very serious".
Companies such as Uber, JP Morgan Chase and HSBC have also dropped out, along with media giants CNN, The Financial Times and The New York Times.
Crime scene investigators leave Saudi consul's residence
Turkish investigators who searched the Saudi consul-general's residence in Istanbul recovered "samples" after examining the premises for more than nine hours, according to sources at the prosecutor's office.
"Whether these were samples of DNA or blood samples is unclear. Apparently, according to sources, these were quite convincing in terms of evidence," said Al Jazeera's Andrew Simmons, reporting from outside the building.
The forensics team scoured the residence, garage and garden as well, Simmons said. Turkish investigators were seen leaving the building carrying boxes and bags.
Sources say there is video evidence that a car drove from the Saudi consulate to the consul general's residence on the day Khashoggi disappeared.
Saudi Consul General Mohammed al-Otaibi and his family unexpectedly left Turkey on Tuesday.
Turkish investigators also re-examined the Saudi consulate after searching it for nine hours on Monday as part of the Khashoggi investigation.
Turkey's interior minister said the investigation's results will be "shared with the world", which could happen this week.
Turkish newspaper gives graphic detail of alleged murder
A pro-government Turkish newspaper published a gruesome recount of Khashoggi's alleged killing at the Saudi consulate in Istanbul.
Yeni Safak reported Khashoggi was killed within minutes of entering the consulate and his torturers severed his fingers during an interrogation. His killers later beheaded and dismembered him, it said, citing an alleged audio recording of the attack.
The newspaper said Saudi Consul General Mohammed al-Otaibi could be heard on the tape telling those allegedly torturing Khashoggi: "Do this outside; you're going to get me in trouble."
The newspaper said one of the men torturing Khashoggi replied: "Shut up if you want to live when you return to [Saudi] Arabia."
A New York Times report cited a senior Turkish official confirming the details published by Yeni Safak.
Turkey has not shared with the US government or European allies graphic audio or video evidence, seven US and European security officials told Reuters news agency.
The United States and allies have collected some intelligence through their own sources and methods, which partly confirms news reports based on leaks of audio recordings, four of the sources said.
Trump denies covering for Saudis
US President Donald Trump denied covering up for ally Saudi Arabia in Khashoggi's suspected murder.
Trump's comments followed the publication in pro-government Turkish media of allegations purporting to confirm Khashoggi was not only murdered by Saudi agents in their consulate in Istanbul, but tortured and dismembered.
"No not at all, I just want to find out what's happening," Trump told reporters in the White House when asked if his cautious approach to the scandal amounts to a cover-up.
"I'm not giving cover at all."
The president said he would get a "full report" from Pompeo on the diplomat's return from meetings with Saudi and Turkish leaders, allowing him to assess what really happened.
"We will probably know that by the end of the week," Trump said.
Mnuchin to decide Thursday if attending Saudi conference
US Treasury Secretary Steven Mnuchin says he will decide on Thursday whether he will attend an investment conference in Riyadh that has been boycotted by global business leaders concerned about Khashoggi's fate.
Mnuchin said he will "revisit the decision again" after reviewing Secretary of State Mike Pompeo's report on the case on Thursday.
Washington Post publishes new Khashoggi column
The Washington Post published a new column by Khashoggi, in which he discussed the importance of a free press in the Middle East.
Governments in the region "have been given free rein to continue silencing the media at an increasing rate", he wrote.
Khashoggi condemned what he called silence from the international community over attacks on press freedom, saying imprisonment of journalists and seizing control of newspapers "no longer carry the consequence of a backlash from the international community".
"Instead, these actions may trigger condemnation followed by silence," he wrote.
Post Global Opinions editor Karen Attiah said she received the column from Khashoggi's assistant a day after he was reported missing.
The newspaper also plans to publish a page dedicated to Khashoggi in its opinions section on Thursday.
US senators press Trump on Saudi business ties
Eleven Democratic senators have sent a letter to Trump and to the Trump Organization seeking a full accounting of any financial ties between the Trump Organization and Saudi Arabia.
"It is imperative that this sanctions determination, and US policy towards Saudi Arabia generally, are not influenced by any conflicts of interest that may exist because of your or your family's deep financial ties to Saudi Arabia," the senators wrote to Trump.