(CNN) The killing of Jamal Khashoggi was "a violently planned" murder that was subsequently covered up, the spokesman for Turkish President Recep Tayyip Erdogan's ruling AK Party said Monday.

Omer Celik, spokesman for the AK party, told reporters at the party's headquarters in Ankara that the perpetrators should be brought to justice, according to Turkey's state news agency Anadolu.

Celik spoke a few hours after CNN published surveillance footage that showed what a Turkish source described as a "body double" leaving the Saudi consulate in Istanbul on the day Khashoggi died. The Saudi operative, said by the Turkish source to be one of a 15-man team sent from Saudi Arabia to kill Khashoggi, was wearing the journalist's clothes and was picked up on surveillance footage at locations around Istanbul.

"Jamal Khashoggi's killing is a violently planned and a very complicated murder, which was being covered up," Celik said. "I hope those responsible for Khashoggi's killing are punished and no one ever thinks of repeating this."

Erdogan will make an announcement on the murder case of Jamal Khashoggi on Tuesday and "nothing about this event will remain hidden," his spokesman, Ibrahim Kalin, told reporters Monday.

"The line our President put since the beginning of this case is very clear," Kalin said. "The investigation will continue until the end."

Surveillance footage shows Jamal Khashoggi (left) as he enters the Saudi consulate. A senior Turkish official told CNN the man on the right, Mustafa Al-Madani, dressed up in Khashoggi's clothes after his death.

Meanwhile, CIA Director Gina Haspel is traveling to Turkey to address the investigation into Khashoggi's death, according to a source familiar with her plans.

Reuters was first to report on Haspel's trip. The CIA did not respond to requests for comment on Monday.

Khashoggi, a Washington Post columnist and US resident, was last seen on October 2, when he walked into the Saudi consulate to obtain paperwork to marry his fiancee Hatice Cengiz.

After weeks of denying any knowledge of Khashoggi's whereabouts, the Saudi government admitted on Friday that he had died in the diplomatic compound. The official line is that he was accidentally killed when a discussion with officials turned into a brawl.

Since then, the Saudi narrative has continued to evolve. A Saudi source close to the royal palace later told CNN that Khashoggi had died in a chokehold. On Sunday, its foreign minister, Adel al-Jubeir, described his death a "murder" and a "tremendous mistake." Saudi Arabia does not know where Khashoggi's body is, he told Fox News.

"The individuals who did this did this outside the scope of their authority," he said. "There obviously was a tremendous mistake made, and what compounded the mistake was the attempt to try to cover up. That is unacceptable in any government."

On Monday, a Saudi source would not confirm or deny that the operative was sent to act as a body double, but continued to maintain that the killing of Khashoggi was not intentional.

Turkish police also confirmed to CNN that an abandoned car at a parking lot in Istanbul's Sultangazi district is part of its investigation into Khashoggi's death.

An officer said while officers have examined the area around the car, a forensics team will return on Tuesday morning to search inside.

Saudi royals offer condolences

King Salman and his son, Crown Prince Mohammad bin Salman, called Khashoggi's son to express their condolences, Saudi state media reported Monday.

The King called Salah Khashoggi, the Washington Post journalist's eldest son, to express "his condolences to the family and relatives of the late Jamal Khashoggi," the state-run SPA news agency reported. The younger Khashoggi "expressed his sincere thanks" to the Crown Prince for his thoughts, according to SPA.

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Salah Khashoggi, who lives in the Saudi city of Jeddah, has been unable to travel outside Saudi Arabia for several months, as his passport had been invalidated, according to sources close to the family. Other members of Khashoggi's family, including his ex-wife and daughter, are currently in Dubai, add the sources.

The journalist's Turkish fiancee, Hatice Cengiz, has been placed under 24-hour police protection, the Istanbul governor's office announced on Sunday.

Turkish authorities will interview an additional 28 consulate staff members on Monday as part of the investigation, state broadcaster TRT said.

Erdogan and US President Donald Trump discussed Khashoggi's death in a phone call over the weekend, Anadolu reported Monday, and pledged to "shed light on all aspects" of the incident.

US Secretary of State Mike Pompeo spoke with Turkish Foreign Minister Mevlut Cavusoglu on Sunday night and again offered US assistance with the Khashoggi investigation, a senior State Department official told CNN.

Trump also discussed the journalist's fate with French President Emmanuel Macron, amid increasing international pressure for a transparent, independent investigation.

The US leader has continued to hedge, offering support for bin Salman, calling him in a Washington Post interview a "strong person" who "truly loves his country" while asserting that "obviously there's been deception and there's been lies" throughout the three weeks since Khashoggi's disappearance.

On Monday, Trump said he had spoken with bin Salman about the investigation into Khashoggi's death, adding that more details will become apparent tonight or tomorrow morning.

"We have people over in Saudi Arabia right now. We have top intelligence people in Turkey," Trump told reporters.

The President also said that a monthlong investigation into Khashoggi's death, which the Saudis requested on Friday, would be too long.

"I think it's a long time. You said, they want a month? That's a long time," Trump remarked. "There's no reason for that."

in a meeting Monday with the Saudi Crown Prince, according to a tweet from Treasury spokesperson Tony Sayegh. Mnuchin also discussed Saudi economic issues, combating terrorist financing, and implementing Iran sanctions, according to the tweet. Treasury Secretary Steven Mnuchin addressed the Khashoggi investigationin a meeting Monday with the Saudi Crown Prince, according to a tweet from Treasury spokesperson Tony Sayegh. Mnuchin also discussed Saudi economic issues, combating terrorist financing, and implementing Iran sanctions, according to the tweet.

In his meeting with the Saudi Crown Prince, @stevenmnuchin1 addressed combating terrorist financing, implementing Iran sanctions, Saudi economic issues and the Khashoggi investigation. — Tony Sayegh (@TreasurySpox) October 22, 2018

Meanwhile, the UK government is under pressure from some British lawmakers to halt its arms sales to Saudi Arabia.

The country's Foreign Secretary, Jeremy Hunt, says that Saudi Arabia's "claim that Mr. Khashoggi died in a fight does not amount to a credible explanation" and despite the UK's "important strategic partnership" with Saudi Arabia, he is willing to act once the final details are known.

"If the appalling stories we are reading turn out to be true, they are fundamentally incompatible with our values. We will act accordingly," he said in Parliament on Monday.

"Actions Britain and our allies take will depend on two things. Firstly, the credibility of the explanation given by Saudi Arabia, and secondly on our confidence that such an appalling episode cannot and will not be repeated."