By Stephen Kalin, Marwa Rashad and Tuvan Gumrukcu
RIYADH/ANKARA (Reuters) - Saudi Arabia's public prosecutor is seeking the death penalty for five suspects charged in the murder of journalist Jamal Khashoggi, as the kingdom tries to contain its biggest political crisis for a generation.
Khashoggi, a royal insider turned critic of Saudi policy, was killed in the country's Istanbul consulate on Oct. 2, after a struggle, by lethal injection, deputy public prosecutor and spokesman Shalaan al-Shalaan told reporters on Thursday.
Shalaan said that de facto ruler Crown Prince Mohammed bin Salman knew nothing of the operation, in which Khashoggi's body was dismembered, removed from the building and handed over to an unidentified "local cooperator".
The whereabouts of Khashoggi's remains are unknown, he said. His family is planning a weekend prayer service without his body.
Following Shalaan's account, the latest of Riyadh's shifting explanations, the U.S. Treasury will announce sanctions on 17 Saudis for their role in the killing, including Saud al-Qahtani, a former top aide to Prince Mohammed, and Istanbul Consul General Mohammed Alotaibi, a source familiar with the plan told Reuters.
Turkey, however, reacted with scepticism and a U.S. senator said it was unbelievable that the killing could not have been carried out without orders. France's foreign ministry, meanwhile, said the investigation was proceeding in the right direction.
The case has sparked a global outcry and tarnished the image of Prince Mohammed.
Shalaan said Khashoggi was murdered after "negotiations" for his return to the kingdom failed, and that the killing was ordered by the lead negotiator after he decided it was unfeasible to remove him from the consulate.
Shalaan said the order to repatriate Khashoggi came from former deputy intelligence chief Ahmed al-Asiri, who was sacked last month.
He said Prince Mohammed "did not have any knowledge" of the killing, a stance reiterated by Saudi Foreign Minister Adel al-Jubeir, who accused Turkey of ignoring Saudi requests for information.
Turkish President Tayyip Erdogan has said the order for the operation came from the highest level of Saudi leadership but probably not King Salman, putting the spotlight instead on his 33-year-old heir.
U.S. President Donald Trump has suggested ultimate responsibility lies with the prince as de facto ruler and has warned of economic sanctions. Asked about that possibility, Jubeir said a distinction should be made between individuals who committed crimes and the government.
Riyadh initially denied any knowledge of Khashoggi's disappearance, then offered contradictory explanations including that he was killed in a rogue operation.
U.S. Democratic Senator Chris Coons dismissed that idea as "utterly incredible" and called for a U.S. investigation using information from Turkish intelligence and other sources. "We should reach our own conclusions, rather than letting the Saudis come up with a different version of events," he said on CNN.
Some details provided on Thursday again contradicted previous versions, none of which mentioned a drug-induced death and one of which called the killing premeditated based on information provided by Turkey.
Turkish Foreign Minister Mevlut Cavusoglu said the measures announced by Saudi Arabia were "positive but insufficient", and repeated Ankara's demand that the 15-man team be tried in Turkey.
An adviser to Erdogan accused Riyadh of trying to cover up the murder. "I don't believe the real perpetrators will be found through Saudi Arabia's investigation," Yasin Aktay said.
Without naming them, Shalaan said the Saudi prosecutor had requested the death penalty for five individuals "charged with ordering and committing the crime, and for the appropriate sentences for the other indicted individuals".
He said 11 of 21 suspects have been indicted and will be referred to court, while investigations of the remaining suspects will continue.
He said a travel ban had been imposed on Qahtani, who coordinated with Asiri, meeting the operatives ahead of their journey to Istanbul to brief them on Khashoggi's activities.
Qahtani has already been fired from the royal court, but four sources based in the Gulf have told Reuters that he is still at liberty and continues to operate discreetly.
A senior government official previously identified the head of the negotiating team as Maher Mutreb, an aide to Qahtani who has appeared in photographs with Prince Mohammed on official foreign visits this year.
Six weeks after the murder, Turkey is trying to maintain pressure on Prince Mohammed, releasing a stream of evidence that undermined Riyadh's early denials.
Turkey says it has recordings related to the killing which it shared with Western allies. One Turkish official told Reuters that officials who heard the recordings, which include Khashoggi's killing and conversations leading up to the operation, were horrified but their countries had done nothing.
Last month, two intelligence sources said Qahtani gave orders over Skype to Khashoggi's killers. More recently, a government source said Qahtani featured prominently throughout the recordings.
Erdogan has said Turkey also played the recordings to Saudi officials, something Shalaan declined to confirm or deny. He said Riyadh asked Ankara to share witness testimonies and hand over Khashoggi's phones.
(Additional reporting by Maha El Dahan and Asma Al Sharif in Dubai, Doina Chiacu in Washington, John Irish in Paris; Writing by Tuqa Khalid and Ghaida Ghantous; Editing by Dominic Evans/Mark Heinrich)