Turkish President Recep Tayyip Erdogan insisted on Monday that Ankara would keep pushing for the truth behind the killing of Saudi journalist Jamal Khashoggi at the Saudi consulate in Istanbul last year, saying some of his killers appeared to be evading justice.

In Washington Post, for whom Khashoggi was a columnist, Erdogan said Turkey still wanted to know where the Saudi journalist’s body was and who had authorised the operation – suggesting it was carried by agents of a “shadow state” in Saudi Arabia.

Eleven Saudi suspects have been put on trial for the murder in secretive proceedings but only a few hearings have been held.

Nearly a year after Khashoggi was killed by Saudi agents sent from Riyadh, Saudi Arabia’s de facto ruler Crown Prince Mohammed bin Salman said in an interview with US broadcaster CBS aired on Sunday that he had “absolutely not” ordered Khashoggi’s killing, although he bore responsibility as a leader of his country.

Khashoggi, who also wrote for Middle East Eye, had become a prominent critic of bin Salman’s policies.

The CIA and some western governments have said they believe the crown prince ordered the operation, an assertion Saudi officials have repeatedly denied.

A United Nations report earlier this year called for bin Salman and other senior Saudi officials to be investigated.

Dangerous precedent

Khashoggi was last seen entering the Saudi consulate in Istanbul on 2 October, where he was to receive papers ahead of his wedding.

Erdogan said the fact that Khashoggi’s killers travelled on diplomatic passports and “turned a diplomatic building into a crime scene” set a dangerous precedent.

“Perhaps more dangerous is the impunity that some of the killers seem to enjoy back in the kingdom,” he wrote, adding that there was a near-complete lack of transparency on the court proceedings.

On 13 October, Khashoggi was dragged from the consul general’s office inside the Saudi consulate in Istanbul and brutally murdered by two men who cut up his body, citing sources close to the investigation.

Erdogan said: “The 15-member assassination squad that murdered Khashoggi inside Saudi Arabia’s consulate in Istanbul and chopped his body into pieces served the interests of a shadow state within the kingdom’s government.”

Twitter bans ex-MBS adviser Qahtani and ‘political spam’ network targeting Qatar

Earlier this month Twitter of former Saudi royal court adviser Saud al-Qahtani, a year after he was sacked over his suspected role in the murder of Khashoggi.

Qahtani ran the royal court’s media centre as well as an electronic army tasked with protecting the kingdom’s image and attacking its perceived enemies online.

He is not among the suspects on trial for the murder of Khashoggi, according to sources familiar with the matter.

His absence from the trial comes after a Saudi royal told WSJ that bin Salman “had no intention whatsoever to let go of Qahtani and was furious when he was fired by his father”.

Erdogan said Turkey continued to see Saudi Arabia as a friend and ally, but that did not mean Ankara would remain silent.