WASHINGTON — The White House relationship with Riyadh is imperiled over the mysterious disappearance of a Saudi writer, and the situation is creating friction between the Trump administration and members of Congress demanding to know if the columnist for The Washington Post was killed inside the Saudi Consulate in Turkey.

Trump said he has talked to officials at the highest level of the kingdom and is “demanding everything” to explain how Jamal Khashoggi, an activist who had been critical of Saudi leaders, vanished after he walked into the consulate in Istanbul to get documents he needed to get married.

Turkish authorities claim Khashoggi, who resided in the United States, was killed by members of an elite Saudi “assassination squad.”

The Washington Post reported that the Turkish government has told U.S. officials that it has audio and video recordings that prove Khashoggi was killed inside the Saudi Consulate this month, according to U.S. and Turkish officials.

The recordings show that a Saudi security team detained Khashoggi in the consulate after he walked in Oct. 2, then killed him and dismembered his body, the officials said.

The audio recording provides some of the most persuasive and gruesome evidence that the Saudi team is responsible for Khashoggi’s death, the officials said.

“The voice recording from inside the embassy lays out what happened to Jamal after he entered,” said one person with knowledge of the recording who, like others, spoke on the condition of anonymity to discuss highly sensitive intelligence.

“You can hear his voice and the voices of men speaking Arabic,” this person said. “You can hear how he was interrogated, tortured and then murdered.”

The kingdom describes the allegation as “baseless.”

But if Saudi Arabia is found to be complicit in his disappearance or death, the warm U.S.-Saudi relationship — and even hopes for Middle East peace — could be upended.

A senior administration official said Friday that the U.S. is in ongoing contact with Turkish and Saudi officials about the case.

Trump said Friday he would bring up the matter with King Salman.

The U.S. believes it is essential that Turkish authorities — with full, transparent support from the Saudi government — are able to conduct a thorough investigation and officially release the results, the official said.

The administration official, who spoke on condition of anonymity, said the U.S. supports Turkish investigators’ efforts, will not prejudge the outcome of the official investigation, but stands ready to assist.

Trump said Thursday the U.S. had “investigators over there and we’re working with Turkey” and Saudi Arabia. But he has provided no details.

Trump has backed Crown Prince Mohammed bin Salman’s ambitious campaign to modernize the conservative kingdom and its economy. Trump’s son-in-law, Jared Kushner, who exchanges phone and text messages with the crown prince, was instrumental in last year’s deal to sell $110 billion in U.S. weapons to the kingdom.

But even before Khashoggi vanished, concerns were mounting in Congress over Saudi Arabia’s policies and the crown prince’s steps to silence his critics. And now there are calls on Capitol Hill for the U.S. to halt arms sales to the kingdom, and Khashoggi’s disappearance could galvanize more opposition from lawmakers and pressure Trump to rethink his relations with Saudi Arabia.

Trump on Thursday pronounced U.S. relations with Saudi Arabia “excellent” and said he doesn’t want to scuttle arms deals with Riyadh because it means tens of millions of dollars pouring into the U.S. economy. He said the kingdom would simply buy the weapons from Russia or China instead.