"Why was the consulate opened not immediately but days later for investigation?" Erdogan said.
Although investigators' lack of access frustrated observers and raised suspicions about Saudi Arabia's denials early on, the rules that prevented Turkish authorities from immediately entering the consulate have long been the framework of international diplomacy and is essential to the work of embassy staff abroad.
It's an agreement that has in the past protected perpetrators of crimes, but that also has prevented illegal interference in diplomatic work.
Erdogan should be well aware of that, given that his own bodyguards escaped prosecution not long ago, relying on the same international convention.
In May, protesters and security guards who accompanied Erdogan during a trip to Washington clashed outside the Turkish ambassador's residence.
After the demonstration attended both by anti-Erdogan and pro-Kurdish activists turned violent, 11 people, including a police officer, had to be treated for injuries. At least two people were arrested.
When footage emerged showing the extent to which the Turkish protective detail had been responsible for the escalation, District of Columbia police were able to identify a number of presidential bodyguards and eventually issued arrest warrants, even as questions mounted about the diplomatic status of Erdogan's security team.
To US prosecutors, the evidence clearly showed that the Turkish bodyguards had "assaulted and kicked protesters who were assembled in front of the embassy." Footage showed the bodyguards kicking and choking people.
But the 1961 Vienna Convention on Consular Affairs similarly clearly lays out the limits of prosecutors in international diplomacy.
Police and security officials are not allowed to enter an embassy or consulate without previously being granted permission to do so by the nation occupying it. Certain bags or letters sent from consulates or embassies may also not be opened by authorities of host nations. And, most importantly in last year's case, immunity also applies to embassy staff members and some other visiting foreign officials.
The clashes last year and Khashoggi's killing on October 2 are somewhat different, given that the Saudis have not argued that the 15 people who travelled to Istanbul acted as diplomats or under diplomatic protection. In this case, Turkey's focus has been on entering space located on its soil, but still inaccessible to its authorities.
Although the cases differ, the measures nations have at their disposal to hold foreign diplomatic workers accountable are the same.
Governments can ask nations to waive the immunity of their staff members. If those efforts fail, they can unilaterally revoke consular clearances or declare ambassadors "persona non grata," which effectively requires them to leave.
It's unclear whether Turkish authorities have evidence against any consular employees still in Istanbul. Citing Turkish media outlets, the Reuters news agency reported last week that the Saudi consul had left the city before Turkish investigators searched the consulate.
"From the US perspective, these immunities protect our diplomats from exposure to foreign judicial systems and ensure that our president and secretary of state can travel abroad without worrying about facing politically motivated criminal or civil cases," University of Virginia associate law professor Ashley Deeks wrote last year.
After last year's clashes in Washington, it was not immediately clear whether Erdogan's bodyguards were also protected by diplomatic immunity.
Although administrative and technical embassy staff members are exempt from prosecutions unless that protection is waived by their nations, some visiting officials do not automatically receive immunity.
For lower-level officials - a category that would apply to bodyguards - a number of factors determine whether diplomatic immunity applies to them; Secret Service agents travelling abroad with US presidents have at times encountered similar challenges.
As officials were debating which rules would apply in last year's case outside the Turkish ambassador's residence, some were already demanding a prosecution regardless of the outcome.
In a letter to the Justice Department, House Foreign Affairs Committee Chairman Edward Royce, (R), said that "agents of foreign governments should never be immune from prosecution for felonious behaviour." His remarks came as the Turkish bodyguards were still in the United States and could theoretically have been prevented from leaving the country.
But two guards who were briefly detained after the clashes were released within hours. Fifteen guards were indicted the following month, but by that time they had left US soil.
US prosecutors have since dropped assault and conspiracy charges against 11 of them.
Erdogan denounced the charges, but last night's remarks indicate that his support for international law appears to fluctuate, depending on the circumstances.
