Investigators examining Altintas' computer have found that just before the murder, he searched for information about US ambassador John Bass. He also collected information about the activities of Russian and American cultural centers in Ankara.
The findings have led investigators to wonder if Altintas was also planning an attack on the US ambassador.
Russian ambassador Andrei Karlov was shot dead by Altintas, who was on leave from the police force at the time of the attack, at the opening of an art exhibition in December.
The Russian Foreign Ministry said it considered the attack a terrorist act, and Russian President Vladimir Putin called the assassination "an assault on Russia and Russian-Turkish relations."
On Tuesday, the Sabah newspaper, citing a source in law enforcement agencies, reported that the Ankara prosecutor's office asked the US Federal Bureau of Investigation (FBI) for assistance in investigating Karlov's murder.
Prosecutors want the FBI to help them hack the iPhone used by the 22-year-old killer. They have also made a written request to Google's Gmail service, asking them to restore messages that were deleted from Altintas' email account two hours after the murder.
In response, the email service said that it wasn't possible to restore the deleted messages. Therefore, Investigators also want the FBI to help them access the messages via the server from which they were deleted.
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