Saudi Arabia's Crown Prince approved the assassination of journalist Jamal Khashoggi, a White House report found.
Mohammed bin Salman viewed the dissident as a threat and backed violence to silence him, it is claimed.
The much-anticipated publication by the Joe Biden administration rubbishes the Crown Prince's previous denial.
Mr Khashoggi was murdered at the Saudi consulate in Istanbul, Turkey, on October 2, 2018.
He had visited the building to obtain paperwork for his impending wedding to fiancee Hatice Cengiz.
Officials first claimed that the journalist, who fled Saudi Arabia in 2017, had left the building, but were later forced to admit he was dead.
Hours earlier a 15-strong hit squad had landed in Turkey, and in November 2018 the CIA ruled that the Saudi Crown Prince had ordered the assassination - a claim he denied.
The Crown Prince did however say he took "full responsibility as a leader in Saudi Arabia, especially since it was committed by individuals working for the Saudi government".
The Saudi government maintains "rogue agents" carried out the killings, with five initially sentenced to death, only to have the ruling commuted to 20 years in prison.
Agnes Callamard, the UN special rapporteur on executions, said Saudi Arabia was responsible for Khashoggi's "premeditated execution".
She also stated there was "credible evidence" implicating the Crown Prince in the killing.
US President Joe Biden has said he intends to "recalibrate" the relationship with Saudi Arabia after Donald Trump failed to take any tough action in the wake of the killing.
He plans to communicate with Saudi King Salman bin Abdulaziz Al-Saud instead of his son, the Crown Prince.
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