"A lot still remains uncertain," Rutte noted to reporters in Copenhagen on Saturday.
"What happened? How did he die? Who is responsible?" he said, adding, "I expect and I hope that all relevant facts will be clear as soon as possible."
A "thorough investigation is necessary," the Dutch PM noted, cited by Reuters.
Khashoggi, a former Riyadh insider who wrote unsparingly of the kingdom's policies including its ongoing war in Yemen, disappeared after entering the Saudi consulate in Istanbul some two weeks ago, and has now been acknowledged by Saudi officials as having "died in a fistfight," according to CNN.