However, questions remained over how much evidence the investigators could turn up at a consulate where a cleaning crew had entered hours before their arrival.
Turkish officials allege he was murdered.
Turkish officials fear Khashoggi was killed and dismembered. There have been suggestions that Khashoggi was previously concerned he was about to be captured by the Saudi court.
The statement did not elaborate.
What did happen to Jamal Khashoggi, according to the king? Britain, France and Germany, which have also tended to prioritize economic ties with Riyadh, issued a joint statement saying they "expect the Saudi government to provide a complete and detailed response".
What evidence Turkish officials could gather at the consulate remained unknown. Worldwide concern continues to grow over the writer's October 2 disappearance.
A Foreign Ministry official had earlier said the team would visit the diplomatic post Monday.
They said there must be a credible investigation to establish the truth and "if relevant" identify those responsible for Khashoggi's disappearance.
"It depends on how well they cleaned it up", Prinz told The Associated Press. "Obviously, he is very, very serious". "That's going to be a problem".
A Turkish official told Reuters on Sunday that the Saudis had said they would allow the consulate to be searched, and that this would happen by the end of the weekend, though he conceded to "flexibility on this date".
Trump said he had spoken with King Salman about Khashoggi, a critic of Saudi policies, and that he was sending Secretary of State Mike Pompeo immediately to meet the king and travel to other places as needed.
"I sounded to me like maybe there could have been rogue killers. We are following the situation closely, and unless a substantially different set of facts emerges, I won't be attending the FII conference in Riyadh".
Trump told journalists. "We're going to try getting to the bottom of it very soon, but (King Salman's) was a flat denial".
President Donald Trump's feud with Saudi Arabia over a missing journalist poses one of the biggest risks to stock market sentiment at the beginning of the week.
Saudi Arabia is facing mounting pressure from the White House and other Western countries to provide answers over the missing Washington Post columnist and US resident.
"The objective of (Sunday's) message broadcasted by the Saudi national media is twofold: one goal is to satisfy the domestic public opinion that Saudi Arabia and its royal family will not be humiliated and the other goal is to send a message to the US", Mitreski, researcher at the University of Sydney, told AFP.
Ford Motor Co. confirms that Executive Chairman Bill Ford will not attend. However, a column published in English a short time later by the general manager of the Saudi-owned Al-Arabiya satellite news network suggested Saudi Arabia could use its oil production as a weapon.
Technology company SoftBank saw its shares drop as the fallout spread to the Japanese conglomerate whose nearly $100 billion Vision Fund is almost half-funded by Saudi Arabia. Khalaf Ahmad Al-Habtoor, an influential United Arab Emirates tycoon, called for an Arab boycott of all USA firms who have withdrawn from the conference.
But the president has also said "we would be punishing ourselves" by canceling arms sales to Saudi Arabia.