State news agency Anadolu said that the officers began searching a two-story building in Termal district in Yalova with the help of sniffer dogs and drones on Monday.
The law enforcement agencies later widened the search and investigation to the adjacent villa, it added.
Crime scene investigators were inspecting a well in the first villa's garden in Samanli village, while images showed fire trucks at the scene.
In a statement, the Istanbul prosecutor said the first villa is owned by a Saudi man who had spoken to one of the murder suspects on October 1. The prosecutor added that this information was the reason given to search the building, Presstv reported.
"It is believed that what was discussed was how to destroy or hide journalist Jamal Khashoggi's body after his dismemberment during this conversation," the statement read.
There have been previous inspections of the Saudi consulate and the consul-general's residence in Istanbul as well as a forest in the city. The latest searches came more than two weeks after pro-government Sabah daily reported that samples taken from the consulate drains showed traces of acid.
President Recep Tayyip Erdogan earlier this month said Turkey had given "recordings" on the murder of Khashoggi to Saudi Arabia, the United States, Germany, France, and Britain. In a televised speech on November 10, Erdogan said Saudi Arabia knew the killer of Khashoggi was among a group of 15 people who arrived in Turkey one day ahead of the October 2 murder.
The contents of the gruesome recording allegedly prove that Khashoggi was grabbed, drugged and dismembered with a bone saw. The voice attributed to a Saudi forensic evidence chief also suggests that others witnessing Khashoggi’s harrowing fate listened to music in order to drown out the sounds.
Turkish media outlets have named the Saudi suspects who flew into Istanbul and left on the same day the journalist was last seen.
Turkish judicial sources have said that Khashoggi was "strangled" as soon as he entered the diplomatic mission and his body was then "cut into pieces" under a "premeditated plan."
A senior Turkish official recently told the Washington Post that the slain journalist’s body was destroyed in acid on the grounds of the Saudi consulate or at the nearby residence of the Saudi consul general. The official, speaking on condition of anonymity, said biological evidence discovered in the diplomatic mission garden supports the theory that Khashoggi’s body was disposed of close to where he was killed and dismembered.
The body of Khashoggi remains missing. A joint Turkish-Saudi investigation into Khashoggi’s fate has made little progress so far.
Khashoggi, a prominent commentator on Saudi affairs who wrote for the Washington Post’s Global Opinions section, had lived in self-imposed exile in the US since September 2017, when he left Saudi Arabia over fears of the Riyadh regime’s crackdown on critical voices.
He was seeking to secure documentation for his forthcoming marriage when he entered the Saudi consulate in Istanbul on October 2, but never came out despite Riyadh’s initial claim that he exited the mission less than an hour after completing his paperwork.
Riyadh initially denied knowledge of Khashoggi’s disappearance, then offered contradictory explanations.
The kingdom, however, later admitted that Khashoggi had been murdered in the consulate during an interrogation by rogue operatives that had gone wrong after diplomatic pressure grew tremendously on Riyadh to give an account on the mysterious fate of its national. However, Saudi Arabia said that it did not know the whereabouts of the body, which is widely believed to have been dismembered.
His death has put the Riyadh regime and Saudi Crown Prince Mohammed bin Salman under strict scrutiny.
The CIA believes bin Salman ordered the killing of Khashoggi who was critical of Saudi Arabia’s de facto leader.