Some background and a new theory:
His fiancé, a Turkish diplomat, is the daughter of a former adviser to Turkey’s Islamist President Recep Tayyip Erdogan. Khashoggi started tweeting pictures of himself with Erdogan advisers. He was also planning to start a Turkish center, funded by the Turks and the Qataris, agitating for change in Saudi Arabia to champion dissent. But many of the dissenters he was championing were Islamists opposed to the attempts by MBS to modernize Saudi economy and society.
Increasingly alarmed, the MBS regime tried to bribe him. “Khashoggi was offered U.S. $9 million to return to Saudi Arabia, with a public guarantee that he would never be harmed. He refused.”
So the Saudis set out to bring Khashoggi back against his will. That’s why they sent the 15-strong squad, who had been alerted to the timing of his consular appointment. The intention was to extract him back to Riyadh, interrogate him and lock him up, probably for many years.
“If they’d wanted to kill him,” my informant said, “they could easily have paid $200,000 to the Chechen mafia in Istanbul who could have taken him out so easily and made it look like a robbery gone wrong.”
There was no kill order from Saudi Arabia. The planes that flew the squad into Turkey were owned by his friend, former Crown Prince Mohammed al Nayaf. Khashoggi would have been locked up and interrogated. They wanted to know who he had talked to and what he had revealed. They say some leaks from Qatar had his fingerprints all over them.
“So they set out to bring him back alive. The pathologist, a member of the inner circle, was there to ensure he remained sedated on the way back to Riyadh.”
But this, according to my source, was where disaster occurred. “The sedative gun malfunctioned and he suffocated from a massive overdose. He was 60 years old, he was overweight, his body couldn’t cope with it.”
http://www.jwire.com.au/the-story-behind-the-story-of-jamal-khashoggi/
Now that makes a lot more sense than sending 15 guys to kill him when two hit men would do.