After initially denying it, Saudi officials have acknowledged that Mr. Khashoggi was killed in the consulate and that it was premeditated, but have continued to deny that Crown Prince Mohammed bin Salman, often known by his initials, M.B.S., knew in advance or had any involvement in the operation. A recording shared by Turkish officials with the C.I.A. captured a member of the kill team instructing a superior over the phone to “tell your boss” that the operation had been carried out.

The lack of an ambassador in either Saudi Arabia and Turkey has been a point of contention since Mr. Khashoggi’s death, underscoring that many important diplomatic posts remain unfilled nearly two years into Mr. Trump’s administration, some because no one has been nominated and others because the Senate has not acted.

Mr. Trump has promised “severe punishment” if it were demonstrated that the Saudis were behind the killing, but he has resisted curbing arms sales as lawmakers in both parties have urged. His Middle East strategy to confront Iran and force Palestinians to make peace with Israel has relied largely on Saudi Arabia, a relationship cultivated by Jared Kushner, his son-in-law and senior adviser, with Prince Mohammed.

General Abizaid, 67, graduated from West Point, where his 1973 yearbook described him as “an Arabian Vince Lombardi” in that he “just couldn’t accept second place.” He spent 34 years in the Army, rising from infantry platoon leader to a celebrated four-star general. As a company commander in Grenada in 1983, he used a bulldozer to advance on a Cuban bunker, a moment later recreated in the Clint Eastwood movie “Heartbreak Ridge.”

As deputy head and then commander of the United States Central Command, he oversaw the early years of the Iraq war, including the quick defeat of the Baghdad government and the capture of Saddam Hussein. His deep understanding of the Middle East made him “our version of Lawrence of Arabia,” as John P. Hannah, Vice President Dick Cheney’s national security adviser, once described him. He coined the phrase “long war” to describe the nation’s struggle with terrorists to make clear to Americans that it would not be a quick battle.