Jamal Khashoggi was killed, dismembered on October 2 in Saudi consulate in Istanbul by 15 agents

Members of the Saudi team that killed journalist Jamal Khashoggi received training in the United States, the Washington Post has reported, revealing other new elements in the death of the newspaper's former contributor.

A critic of the Saudi regime, Khashoggi was killed and dismembered October 2 in the Saudi consulate in Istanbul by a team of 15 agents sent from Riyadh. His body has never been recovered.

After having denied the murder, Saudi Arabia said the operation was carried out by agents who were out of control. A trial of 11 suspects opened earlier this year in Saudi Arabia.

But much of the case remains shrouded, beginning with the role of Saudi Arabia's powerful crown prince and de facto ruler, Mohammed bin Salman.

The US Senate, after a closed-door briefing by the CIA, adopted a resolution naming the crown prince as "responsible" for the murder, while President Donald Trump has refused to publicly take a stand.

According to Washington Post columnist David Ignatius, a Saudi who closely read the transcript of a recording from a bug placed in the consulate by Turkish intelligence said it indicates the plan was to kidnap Khashoggi and bring him back to Saudi Arabia for detention and interrogation.

A note in the transcript says an injection was administered to Khashoggi, which the Saudi source said was probably a powerful sedative.

A bag was then placed over his head, and Khashoggi screamed: "I can't breathe, I have asthma. Don't do this." According to the Post, he died soon after.

The transcript describes a buzzing noise, perhaps an electric saw used to dismember the journalist.

According to Ignatius, who said he interviewed more than a dozen American and Saudi sources who spoke on condition of anonymity, some members of the Saudi Rapid Intervention Group received training in the United States.

"The CIA has cautioned other government agencies that some of this special-operations training might have been conducted by Tier 1 Group, an Arkansas-based company, under a State Department license," he said.

"The training occurred before the Khashoggi incident, as part of ongoing liaison with the Saudis, and it hasn't been resumed."

He said several other US-Saudi security exchange programs also have been suspended.