Turkey will not allow a "cover-up" after Saudi Arabia confirmed that journalist Jamal Khashoggi died following a fight at its consulate in Istanbul.
The deputy head of Turkey's ruling party, Numan Kurtulmus, said authorities would share evidence they have gathered about Mr Khashoggi's death.
Turkish government sources have alleged Mr Khashoggi was tortured and murdered by a hit squad flown in from Riyadh, something the kingdom has denied.
But until Friday night the Saudis had not provided an alternative explanation for what happened to the Washington Post contributor and vocal critic of the kingdom, who was last seen entering the consulate on October 2 to collect paperwork for his upcoming marriage.
They have now said Mr Khashoggi died following a "fist fight" at the consulate, an explanation US President Donald Trump said was "credible".
The UK Foreign Office said it is considering its "next steps" following the announcement.
Saudi Arabia, a key ally and trading partner for many western states, said 18 suspects were in custody and that intelligence officials had been fired, a move Mr Trump described as a "good first step".
The whereabouts of his body remains unknown. Amnesty International said Saudi Arabia should "immediately produce" it so independent forensic experts can conduct an autopsy.
What have the Saudis said?
Saudi state television reported on Friday night that a primary investigation into the Washington Post columnist's disappearance found he died after a fight broke out in the consulate in Turkey.
This is the first time the Saudi's have admitted he died in the consulate.
The Saudis still reject some of the conclusions made by Turkish investigators about how Mr Khashoggi died, according to ITV News Security Editor Rohit Kachroo.
So far, 18 Saudi nationals have been arrested and deputy intelligence chief Ahmad al-Assiri and Saud al-Qahtani, a senior aide to Crown Prince Mohammed bin Salman, have been dismissed, state TV reported.
Saudi King Salman has also ordered the formation of a ministerial committee, headed by Crown Prince Mohammed, to restructure the intelligence services.
How did President Trump respond?
The US President was asked if the Saudi explanation was credible at a meeting of industry leaders on Friday.
He responded: "I do."
Mr Trump said the arrests made over his death were a "good first step," but that what happened was "unacceptable."
However, he reiterated the importance of America's arms deals with the kingdom, saying he would prefer not to hurt American companies and jobs.
"Congress is very interested in this one and we'll be working with Congress.," Mr Trump said.
"But I would prefer if there is going to be some form of sanction or what we may determined to do, if anything, because this was a lot of people they're talking about people pretty high up. But I would prefer that we don't use as retribution canceling $110 billion worth of work, which means mean 600,000 jobs."
On Capitol Hill, politicians including Trump ally Senator Lindsey Graham expressed scepticism about the Saudi account.
“First we were told Mr Khashoggi supposedly left the consulate and there was blanket denial of any Saudi involvement,” Mr Graham tweeted on Friday. “Now, a fight breaks out and he’s killed in the consulate, all without knowledge of Crown Prince.
"It's hard to find this latest 'explanation' as credible."
What has the reaction been in the UK?
The Foreign Office said it was considering its "next steps".
A spokesman said: "We send our condolences to Jamal Khashoggi's family after this confirmation of his death.
"We are considering the Saudi report and our next steps.
"As the Foreign Secretary has said, this was a terrible act and those responsible must be held to account."
Foreign Secretary Jeremy Hunt earlier warned there would be "consequences" for the UK's relationship with Saudi Arabia if it was found the journalist was murdered.
Labour's shadow foreign secretary, Emily Thornberry, called for action to be taken, tweeting: "The Saudi lies and impunity must stop here."
Liberal Democrats leader Sir Vince Cable said: "This situation gets murkier and murkier.
"The UK's heavy reliance on Saudi Arabia for arms sales is embarrassingly compromising in these circumstances.
"The Government should have already suspended arms export licences to Saudi Arabia given the outrages in Yemen. This reinforces the argument for loosening the bonds to the regime."
So what will happen to the Turkish investigation now?
Turkish government sources have previously alleged Mr Khashoggi was tortured and murdered by a hit squad flown in to Istanbul from Riyadh.
The key question now will be whether the Turks continue to pursue this line of enquiry.
The deputy head of Turkey's ruling party has said the country will "never allow a cover-up" and that authorities would share evidence they have gathered about the killing with the world.
Numan Kurtulmus, of the ruling Justice and Development Party, also said he thinks "it's not possible for the Saudi administration to wiggle itself out of this crime if it's confirmed".