On 2 October, Jamal Khashoggi, a well-known journalist and critic of the Saudi government, walked into the country's consulate in Istanbul. He has not been seen since.
Turkish officials believe he was murdered by a team of Saudi agents inside the building and say they have evidence, including gruesome audio recordings, to back this up.
After initial denials and claims that he had left the consulate shortly after arriving, Saudi Arabia has now admitted the journalist is dead.
The kingdom says Khashoggi was killed in a "rogue operation" that the leadership had not been aware of.
The steady stream of disturbing allegations, along with the complex diplomatic situation, means that it can be difficult to keep track of the full story.
So here is what we know about the case.
Who was Jamal Khashoggi?
A prominent journalist who covered major stories including the Soviet invasion of Afghanistan and the rise of Osama Bin Laden for various Saudi news organisations.
For decades, he was close to the Saudi royal family and also served as an adviser to the government.
But he fell out of favour and went into self-imposed exile in the US last year. From there, he wrote a monthly column in the Washington Post in which he criticised the policies of Crown Prince Mohammed bin Salman.
Who was Jamal Khashoggi?
In his first column for the newspaper, Khashoggi said he feared being arrested in an apparent crackdown on dissent overseen by the prince since he became first in line to succeed his father King Salman.
"The people being arrested are not even being dissidents, they just have an independent mind," he told the BBC's Newshour programme just three days before he disappeared.
Why was he at the consulate?
He first visited the Saudi consulate in Istanbul on 28 September to obtain a document certifying that he had divorced his ex-wife, so that he could marry his Turkish fiancée.
But he was told he would have to return and arranged to come back on 2 October.
"He did not mind walking into the Saudi consulate in Istanbul because he did not believe that something bad could happen on Turkish soil," his fiancée, Hatice Cengiz, wrote in the Washington Post.
"Jamal was hardly concerned ahead of his second visit."
The journalist who vanished into a consulate
He was seen on CCTV arriving at 13:14 local time for his appointment, which was scheduled for 13:30.
He reportedly told friends that he had been treated "very warmly" on his first visit and reassured them that he would not face any problems.