France, the United States and Egypt all quickly stepped in - and Hariri was sent back to Lebanon.
That afternoon Hariri delivered his pre-written resignation speech on Saudi television, according to the report.
One official said Ketermaya residents also believed Msallem had raped a 15-year-old local girl a month earlier, but that report could not be independently confirmed.
There was no immediate word of arrests in the attack.
Mohammed bin Salman allegedly subjected Hariri to demeaning pressure and pre-wrote his resignation speech, which blamed Iran for the departure.
The government also allegedly held the Lebanese official captive to be sure he would go through with the resignation.