In his remarks, Mr. Erdogan showed deference to the Saudi king, but he made it clear that he had no intention of dropping the case.

On the same day, Crown Prince Mohammed bin Salman, above center, whom Western officials suspect of authorizing the killing, received a standing ovation at an investment conference in Riyadh. And he had a choreographed handshake with Mr. Khashoggi’s son, Salah, who seemed pained and to have little choice.

But pressure is building. “The worst cover-up ever” is how President Trump described the Saudi explanation for Mr. Khashoggi’s death, and the U.S. revoked the visas of 21 Saudi suspects.

Meanwhile, Saudi Arabia’s regional allies, including Israel and the United Arab Emirates, are starting to worry that the diplomatic crisis could hinder their own agendas.