The board said Saudi Arabia has to identify the 15 officials who were at the consulate and exactly what happened inside.
Over the past year Khashoggi used his platform as a Washington Post columnist to criticize the policies of Saudi Arabia's powerful young crown prince, from the war in Yemen to the arrest of women's rights advocates.
Jamal Khashoggi, a Saudi journalist and Washington Post contributor, has been missing since last week after he entered the Saudi consulate in Istanbul.
"I have raised Jamal's disappearance personally with the Saudi ambassador, and while we await more information, know we will respond accordingly to any state that targets journalists overseas", he wrote.
Mahoney said Khashoggi's disappearance is "designed, in a very brutal way, to send a message 'if you speak out against the Saudi government, if it could happen to him, it could happen to you"'. "Jamal is a Saudi citizen whose safety and security is a top priority", he said.
Mr Khashoggi was last seen visiting the consulate last week and Turkey says he may have been murdered there.
"We call on the government of Saudi Arabia to support a thorough investigation of Mr. Khashoggi's disappearance and to be transparent about the results of that investigation", he said.
The state-run Saudi Press Agency early Sunday morning carried a statement from the Istanbul Consulate that "strongly denounced these baseless allegations", and expressed doubt that they came from Turkish officials that are informed of the investigation or are authorized to comment on the issue.
The agreement came after Turkey's strongman leader Recep Tayyip Erdogan demanded that the Saudis prove that Khashoggi left the consulate alive.
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Jackson was a special education teacher in Amsterdam, said Santabarbara, who represents the part of NY where the crash happened. Mr Cuomo also told a news conference that the driver did not have the appropriate licence for it.
Turkey has asked for permission to search Saudi Arabia's consulate in Istanbul, broadcaster NTV said on Monday.
The head of the Turkish-Arab Media Association, Turan Kislakci, told the New York Times that Turkish police officers providing security for the consulate had checked their security cameras and did not see the journalist leave on foot.
"If he's in Saudi Arabia, I would know that".
Turkey said on Tuesday it planned to search Saudi Arabia's consulate in Istanbul, where Khashoggi vanished last week after entering the building to request paperwork.
The former government adviser, who turns 60 on October 13, has lived in self-imposed exile in the United States since a year ago to avoid possible arrest.
The US president told reporters on Monday: "Hopefully that will sort itself out".
"We have to get an outcome from this investigation as soon as possible", Mr Erdogan told a news conference in Budapest.
Saudis are, perhaps, trying to ideal their excellence in furtherance of their plans and the world must expect more covert operations by Saudi Arabia in a not-so-distant future with Iran as its primary target.
The alleged murder, cloaked in deep mystery, assumes more global significance because Khashoggi was a high-profile journalist with penetrating worldwide connections.