Andrei Karlov, the ambassador to Turkey, was killed while giving a speech at an art gallery in Ankara three days ago by 22-year-old off-duty police officer Mevlut Mert Altintas. According to MacReports, Turkish police approached Apple about unlocking an iPhone 4s that was recovered from the shooter.
The device is locked with a 4-digit passcode, but it's unclear if it runs iOS 8.0+ or one of the earlier iOS editions that don't enforce full disk encryption.