The head of a group representing Turkish-Arab journalists said Sunday that they were in possession of evidence that shows the missing Saudi journalist was murdered.

Speaking to journalists in front of the Consulate General of Saudi Arabia in Istanbul, Turan Kislakci -- head of the Turkish-Arab Media Association (TAM) -- said they were informed that Jamal Khashoggi was “brutally murdered”.

The journalist and regular columnist for the Washington Post has been missing since he entered the Saudi consulate in Istanbul on Oct. 2.

Kislakci said they received the news two days ago but had waited for confirmation.

“We got the confirmation of the information yesterday [on Saturday]. It is true that Jamal Khashoggi was murdered.

“A second account says that he was murdered very brutally,” he said without specifying what or how the association came across the information.

The Consulate of Saudi Arabia has denied the claims, focusing namely on a Reuters report on its Twitter account. 

"An official source at the consulate has denied accusations reported by Reuters, attributed to Turkish officials' statements, that Saudi citizen Jamal Khashoggi was killed at the Saudi consulate in Istanbul," said the Saudi consulate on its Twitter account.

Saudi police officers came to the consulate building on Sunday, and stayed inside for two hours, according to an Anadolu Agency correspondent on the ground.

Khashoggi is known to have been critical of Saudi domestic and foreign policies.

The Turkish police in Istanbul has been keeping an eye on the comings and goings at the Saudi consulate since the time -- according to the journalist's fiancee -- Khashoggi entered the building. 

The Chief Public Prosecutor’s Office in Istanbul initiated an investigation on the day of the incident while the consulate also said on Twitter that it was working in coordination with Turkish authorities.