Turkish investigators probing the disappearance of Saudi journalist Jamal Khashoggi were checking flights records and surveillance video seeking to trace the movements of suspected Saudi agents believed to be at the centre of the mystery.
A week after Khashoggi was last seen publicly entering the Saudi Consulate in Istanbul, a growing front of diplomatic pressure and forensic efforts have produced sweeping suspicions but no definitive clues to Khashoggi's fate.
Turkish investigators think Khashoggi, 59, was killed shortly after he entered the consulate on October 2 and his body later removed from the premises, according to a US official and sources close to the investigation.
The Saudi Government denies any involvement in Khashoggi's disappearance.
Another possible layer in the investigation emerged with a report by Sabah - a pro-government Turkish newspaper with connections to President Recip Tayyip Erdogan - of two private jets arriving from Saudi Arabia on the day Khashoggi was last seen.
Turkey's Foreign Ministry said it now wants to inspect the consulate in Istanbul's Levent district and walk the same steps taken by Khashoggi, a writer and critic of Saudi Arabia's leadership.
A statement from Turkish Foreign Ministry spokesman Hami Aksoy said Saudi authorities were "open to cooperation" and would allow an examination of the consulate's grounds. It was not clear when the search would take place.
A closed-circuit television camera image emerged that a person close to the investigation said showed Khashoggi's last known seconds in public - as he was stepping through a door to enter consulate for an appointment to get administrative documents for his upcoming marriage to his Turkish fiancee.
Turkish investigators also are trying to nail down the exact movements of 15 Saudi nationals who arrived in Istanbul the same day and are suspected of having a role in Khashoggi's disappearance.
A report in Sabah said the team members arrived from Riyadh, the Saudi capital, in two private Gulfstream IV airplanes.
One plane, with nine passengers, landed before Khashoggi entered the consulate about 1 pm local time, and the other plane, with six passengers, arrived afterward, according to the flight manifests, the newspaper reported.
The veracity of the report could not immediately be confirmed, but a person with knowledge of the investigation corroborated some of its details.
"The team that arrived with the first plane checked in and left their belongings at two separate hotels near the Saudi Arabian Consulate," the Sabah report said. "Those who arrived with the second plane went directly to the consulate and returned to the airport."
Two and a half hours after Khashoggi entered the consulate, six vehicles left the site, Sabah reported.
"There were 15 Saudi officials and intelligence workers in the vehicles. A Mercedes Vito with tinted windows and another vehicle went to Consul-General's Mohammad al-Otaibi's residence 200m away" and stayed at Otaibi's residence for four hours, the report continued.
Turkish employees at Otaibi's residence were "hastily" told to leave that day, the report added.
Both planes left Istanbul that evening. One stopped in the United Arab Emirates and the other stopped overnight in Egypt, according to the report.
It added that investigators were examining security cameras near the hotels, tracking the movements of the vehicles and also looking into the possibility that Khashoggi was abducted with the help of another country's security services.
The mystery has captured growing international attention because of Khashoggi's prominence and a feud between Turkey and Saudi Arabia, both regional powers.
US President Donald Trump, a close ally of Saudi Crown Prince Mohammed bin Salman, said he would be talking to the Saudi Government "soon" about Khashoggi, who has contributed to the Washington Post's Global section,
"I know nothing" other than what had been reported about the case, Trump added.
In another sign of the growing global interest, the BBC took the unusual step of broadcasting off-the-record comments Khashoggi made during an interview with the broadcaster three days before his disappearance.
"We wouldn't normally broadcast an off-air conversation, but we've decided to make an exception, in light of the current circumstances," the BBC said in a note published on its website.
In Geneva, UN officials expressed "grave concern" over Khashoggi's status and called for an international investigation.
"Those responsible - perpetrators and masterminds - should be identified and brought to justice," said a statement by three UN officials, including Agnes Callamard, the special rapporteur on summary executions.
Federica Mogherini, the European Union's foreign-policy chief, also told reporters in Lisbon that Europe expects "a full-out investigation and full transparency from Saudi authorities on what happened," the Reuters news agency reported.
In London, the British Foreign Office issued a warning to Saudi Arabia of diplomatic fallout if the allegations prove true. "Friendships depend on shared values," said the statement.
Saudi officials have called the accusations "baseless" and "outrageous."
"We have seen over the last few days various malicious leaks and grim rumours flying around about Jamal's whereabouts and fate," the Saudi ambassador to the United States, Khalid bin Salman, said in a message to journalists.
"The reports that suggest that Jamal Khashoggi went missing in the Consulate in Istanbul or that the Kingdom's authorities have detained him or killed him are absolutely false, and baseless," the message said.
"The first reports out of Turkey were that he exited the Consulate and then disappeared," the statement added. "The accusations changed to the outrageous claim that he was murdered, in the Consulate, during business hours, and with dozens of staff and visitors in the building."
"I don't know who is behind these claims," he said. "Nor do I care frankly."
Erdogan has demanded that Saudi Arabia prove that Khashoggi left the consulate on his own.
In the past, Erdogan himself has faced international denunciations over the treatment of Turkish journalists, who have been jailed or forced out of their jobs by his government.
US Secretary of State Mike Pompeo in a statement said that "we have seen conflicting reports on the safety and whereabouts" of Khashoggi.
Pompeo called on the Saudi Government "to support a thorough investigation of Mr Khashoggi's disappearance and to be transparent about the results of that investigation."