UN human rights experts called Tuesday for an investigation into the disappearance of Saudi journalist and government critic Jamal Khashoggi in Istanbul.

Khashoggi has not been seen since his fiancee saw him enter the Saudi Arabian consulate in Istanbul on October 2. Sources in Turkey believe that Khashoggi was killed in a state-sponsored murder after entering the consulate. UN experts are concerned that Khashoggi’s disappearance and the allegations of Saudi Arabia’s involvement are related to his criticism of Saudi policies. They are also calling on Saudi and Turkish authorities to cooperate with one another to fully investigate this case.

US Secretary of State Mike Pompeo said that the State Department has been communicating with Saudi Arabia regarding the issue and is calling on Saudi Arabia to support an investigation. US President Donald Trump has also expressed that he plans to speak with Saudi officials regarding the disappearance. Vice President Mike Pence commented on the issue saying, “Violence against journalists across the globe is a threat to freedom of the press & human rights.”

The Turkish Foreign Ministry has released a statement condemning the journalist’s disappearance and claiming that “[Turkey] can conduct an examination in these premises with the consent of the head of the diplomatic mission.” It plans to move forward with its search of the Saudi consulate soon.