Turkish media outlets have published CCTV footage which they say shows evidence of a plot linked to missing Saudi journalist Jamal Khashoggi.
It shows men said to be Saudi intelligence officers entering and leaving Turkey via Istanbul airport.
Mr Khashoggi, a US resident and critic of the Saudi monarchy, entered the Saudi consulate in Istanbul on 2 October and has not been seen since.
Turkish authorities say Mr Khashoggi was killed. Saudi Arabia denies this.
On Wednesday US President Donald Trump said he wanted to “get to the bottom” of the case, adding: “We cannot let this happen to reporters, to anybody.”
He said the situation was “serious” and wished to invite Mr Khashoggi’s fiancée, Hatice Cengiz, to the White House.
What else does the video show?
Broadcast by Turkey’s TRT World channel and apparently garnered from security cameras, the footage shows vehicles driving up to the consulate, including black vans thought to be central to inquiries.
Groups of Saudi men are seen entering Turkey via Istanbul airport, checking in at hotels and later leaving the country.
Turkish investigators are looking into two Saudi Gulfstream jets that landed at the airport on 2 October. The video shows aircraft waiting on the tarmac.
Mr Khashoggi was visiting the consulate to finalise his divorce so he could marry Ms Cengiz.
He is seen on the video entering the consulate. His fiancée waits outside.
Turkey’s Sabah newspaper reports that it has identified 15 members of an intelligence team it says was involved in the Saudi’s disappearance. Among them was a forensics expert, it says.
The BBC’s Mark Lowen says one of the men was once posted to London.
Police are reported to be examining 150 security cameras as part of their investigation.
Some local media have also been reporting that Mr Khashoggi may have been abducted rather than killed.
Turkey says it will conduct a search of the Istanbul consulate, while Saudi Arabia’s foreign ministry said the country was “open to co-operation” and a search of the building could go ahead.
Ankara is demanding that Saudi Arabia prove Mr Khashoggi left the building, while not providing definitive evidence to support the claim he was killed inside.