– Defense Secretary Jim Mattis said he received assurances from Saudi Arabia’s top diplomat that the kingdom would conduct a full and complete investigation into the slaying of Saudi journalist and dissident Jamal Khashoggi.

Mattis met Saudi Foreign Minister Adel al-Jubeir over lunch Saturday at a security conference in Bahrain. Their discussion came after Mattis condemned Khashoggi’s killing during a speech at the event and warned that such extralegal behavior risked destabilizing the Middle East.

“We discussed it,” Mattis said, recounting the conversation with Jubeir while traveling on Sunday to the Czech Republic. Their discussion, Mattis said, underscored “the need for transparency, a full and complete investigation.”

“He said, ‘We need to know what happened.’ It was very collaborative, in agreement,” Mattis added.

The discussion came after Jubeir called the global reaction “fairly hysterical” in response to questions at the security conference about the killing. The top Saudi diplomat suggested people were jumping to conclusions about guilt before Riyadh had finished its investigation.

“We will know the truth,” Jubeir said. “We will hold those responsible accountable. And we will put in place mechanisms to prevent it from happening again.”

Khashoggi, a critic of the Saudi government who had fled the kingdom and taken up residency in the U.S., entered the Saudi Consulate in Istanbul on Oct. 2 to retrieve paperwork for his upcoming marriage.

Turkish officials say a “hit squad” of Saudi agents dispatched from the Gulf killed Khashoggi in the consulate and dismembered his body. Turkey says it has secret recordings of the events, which Turkish officials recently played for CIA Director Gina Haspel.

Turkey’s well of information about the killing has put pressure on the Saudis to reveal what they know about what appears to be an extrajudicial state-sanctioned killing.