He called on Mickelson to “be a man, step up, accept the truth of who you’re getting in bed with.”

The Saudi government has long denied any involvement in the Sept. 11 attacks. The Sept. 11 Commission, in its 2004 report, found “no evidence that the Saudi government as an institution or senior Saudi officials individually funded” Al Qaeda, which carried out the attacks. But there has been speculation of involvement by other, lower-ranking officials, and an F.B.I. investigation discovered circumstantial evidence of such support, according to a 2020 report by The New York Times Magazine and ProPublica.

Tim Frolich, a banker from Brooklyn who escaped from the 80th floor of the south tower but severely injured his left foot and ankle while running from the tower’s collapse, said the golfers had been “bought off” and were accepting “blood money” from the LIV series. The Saudi-sponsored tour offered signing bonuses, some reported to be in the nine figures, to lure some golfers like Mickelson from the PGA Tour.

“This is nothing more than a group of very talented athletes who appear to have turned their backs on the crime of murder,” said Frolich, who will turn 58 this month.

Mickelson was not made available to reporters on Thursday. In an interview published in February, he told his biographer, Alan Shipnuck, that the Saudis were “scary” and had a “horrible record on human rights,” including the 2018 killing and dismemberment of the Washington Post columnist and dissident Jamal Khashoggi. Mickelson later apologized for his remarks. He joined LIV Golf in June.

No official attendance figures were given for the three-day tournament’s opening round, played under a cloudless sky with temperatures in the 70s. But the crowd to watch mostly aging players in decline was perhaps only a third of the daily attendance of 25,000 or so at a typical event on the rival PGA Tour. Mickelson, 52, finished the round at three over par, eight strokes behind the leader, Carlos Ortiz of Mexico. Still, Mickelson has a vocal and dedicated following.

A number of spectators interviewed said they were simply interested in seeing a sporting event and avoiding geopolitics.