Saudi Arabia’s explanation on Saturday only added to the international uproar over the killing of the dissident Jamal Khashoggi in Istanbul. President Trump appeared to step back from an earlier expression of confidence in this new description of events that Mr. Khashoggi was strangled after a fistfight — skeptics focused on apparent gaps in the narrative and Turkey threatened to undermine the already shaky Saudi account with its own rival investigation.

Doubters questioned why it took 18 days after Mr. Khashoggi disappeared in the Saudi Consulate in Istanbul for the royal court to admit knowledge of his fate — after insisting for two weeks that he had left the consulate freely after a brief visit. Nor did the Saudis explain why Mr. Khashoggi, a 60-year-old writer, sought to resist in a fight against multiple Saudi security agents.

Although the Saudis say that the mission in Turkey was carried out without the specific authorization or awareness of Crown Prince Mohammed bin Salman, 33, the emerging account failed to explain the apparent connections of at least four suspects to the prince’s security detail. The Saudis also offered no explanation for why a doctor specializing in autopsies was sent on the mission, rather than one who treats live patients or manages forensic evidence.

But the most decisive blow to the credibility of the Saudi account could come from Turkey. Turkish officials say they have audio recordings and other evidence that could severely discredit the Saudi narrative and the crown prince by showing that the team executed a deliberate plan to assassinate and dismember Mr. Khashoggi in the consulate.