As the investigation into the murder of the Russian ambassador to Ankara last year hit a wall, new information on the case shows his assassin had also researched information on John Bass, the incumbent U.S. ambassador to Turkey, apparently as a potential target.

Mevlüt Mert Altıntaş, an off-duty policeman, was killed in a shoot-out with security forces after he shot dead Russian Ambassador Andrei Karlov at a ceremony in an Ankara art gallery on Dec. 19, 2016. The murder, which came during a thaw in Turkish-Russian relations previously strained due to the downing of a Russian jet in 2015, remains a mystery, though investigators believe Altıntaş is linked to the Gülenist Terror Group (FETÖ) also behind the July 15 coup attempt in the country. Investigators now hope to retrieve the data in Altıntaş' cellphone with the aid of an Israeli technology company specialized in breaking codes in encrypted phones. The Federal Bureau of Investigation (FBI) will also provide assistance to Turkish authorities to trace the deleted emails of Altıntaş. The murderer destroyed all his digital footprints, from his social media accounts to emails, before he donned a suit and sneaked into the art gallery posing as a bodyguard for Karlov. Security forces managed to retrieve part of the deleted data.

An initial inquiry shows that, apart from the location of the art gallery where Karlov would speak along with information about the Russian ambassador, Altıntaş also made online searches related to John Bass. Security sources have not revealed what the exact nature of the searches on Bass was.

Altıntaş also made online searches about an American cultural association in the capital Ankara before the murder, according to the investigators.

In the latest development regarding the murder, a Russian woman allegedly linked to Altıntaş was arrested by police in Ankara following her detention last month.

The woman, identified as Ekaterina B. had contact over the phone with Altıntaş. Their phone calls date back to November, 2016. Ekaterina B., 33, was also accused of running a prostitution ring catering to wealthy businessmen in Ankara. Police are still analyzing the "digital evidence" and are working to determine the nature of the ties between Altıntaş and Ekaterina B., who also has ties to the local Russian Culture Center.

Three other suspects, including two police officers, have already been remanded into custody.