Was the killer of the Russian ambassador silenced?

Shortly after a breaking story on the Russian news site Sputnik on Dec. 21 about the al-Nusra Front's claiming of responsibility for the assassination of Andrey Karlov, the Russian ambassador to Ankara, on Dec 19, it was understood that the claim was fake.

Before it was understood that it was fake, I was speaking to a ranking security source who was saying that the way the claim of responsibility was made did not fit the method of al-Nusra, the Syrian branch of al-Qaeda. "They always claim responsibility on their website, Minaret ul-Beydha [The White Minaret], not random letters like this," the source said. 

The security source, who asked not to be named, also said terrorist organizations like al-Qaeda or the Islamic State of Iraq and Levant (ISIL) were "after scores, the highest possible number of people that they can kill, whether it is a suicide attack or not. The Berlin attack is an example of that, they attack without discrimination. In this case, the killer's sole target was the Russian ambassador. After he fired almost all the bullets in the cartridge of his pistol [a total of 11, with nine of them hitting the body of Karlov, according to the forensic report -MY], he asked the crowd who were there for the exhibition to leave, saying he 'had no problem with them,' which is not typical for the method of Salafi jihadists."

Earlier, another source told me that "after examining the videos of the assassination and the aftermath in the building over and over again," there was probably another person in the photograph exhibition in connection with the murderer, Mevlüt Mert Altıntaş, a 22-year-old police officer, acting as the instructor and/or the overseer of the attack. 

"Up until a moment the killer was standing there behind the...