Washington Post journalist Jamal Khashoggi went missing in Turkey last week, and some fear he was murdered for his columns critical of Saudi Arabia. The Turkish government has pointed the finger directly at the Kingdom.

"The burden lies with Saudi Arabia to prove that [Khashoggi] is still alive," Kahraman Haliscelik, Press Advisor to the Ministry of Foreign Affairs, told CBS News.

Khashoggi was last seen in the Saudi consulate in Istanbul. The Committee to Protect Journalists (CPJ) had already been documenting the rise of harsh treatment of journalists in Saudi Arabia. It says there were seven imprisoned last year, and nine this year.

Get Breaking News Delivered to Your Inbox

"The worrying trend that we see is a crackdown on critical and independent journalism in Saudi and about Saudi," Robert Mahoney, Deputy Executive Director of CPJ, told CBS News. "It is a very repressive place."

He said that there is no surprise that Riyad is looking to quash criticism, but this case is beyond the sad but true usual jailing of journalists.

Saudi journalist Jamal Khashoggi in 2015. AP

"This is an incredible escalation if these stories are true," Mahoney said. "We have had cases where journalists are killed in another country, but no one as prominent as this, not a U.S. resident who was writing for the Washington Post. He is a journalist but he was also from the Saudi establishment before the present Crown Prince came."

Mahoney said that the disappearance of Khashoggi 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.'"

Turkey has asked to search the Saudi consulate and has opened a criminal investigation.

A Saudi official repeated to CBS News on Monday the Kingdom's flat denial of any involvement in Khashoggi's disappearance, calling his whereabouts "a matter of grave concern to us."

"With no body, there is no crime ... is the way the Saudis are treating the case right now," Mahoney said.