Update: MacReports says the Russian team could not technically hack the 4-digit pass code, however, they have been able to retrieve data from the device by using other means, which they have not divulged.

Original report: Russian cyber experts have reportedly helped Turkish authorities in unlocking an iPhone 4s recovered from Mevlut Mert Altintas, the Turkish assassin who gunned down Russian ambassador Andrey Karlov in Ankara earlier this week.

The authorities have not revealed what has been found on the phone and whether it is of any use to the investigation, according to MacReports.

Earlier, there were conflicting media reports about Apple being asked to unlock the phone. 9 to 5 Mac says that Apple was never requested for any such bypass and Russia offered to attempt to break the four-digit passcode on the recovered iPhone, which it has done successfully.

The latest incident is a reminder of the San Bernandino shooting suspect Rizwaan Farook's phone unlocking controversy, in which Apple refused to help the FBI bypass an iPhone 5C belonging to the shooter.

However, the iPhone 4s used by Altintas is a rather old model and does not have a Secure Enclave or a Touch ID sensor. A Secure Enclave performs key management for encrypted files, where each encrypted file has a unique key, which in turn is encrypted with another key derived from the device UID and the user's passcode.

Karlov was killed by Altintas, an off-duty cop, inside an art gallery while the ambassador was on the podium giving a speech. Altintas used his police ID to gain access to the gallery and shouted "Don't forget Aleppo" after killing the ambassador. He was eventually killed in a shoot-out with Turkish special forces and now authorities are trying to determine whether it was a one man act or if he was affiliated to any group.

Andrey Karlov Mevlut Mert Altintas ambassador
The gunman was been identified as 22-year-old riot police officer, Mevlut Mert Altintas Hasim Kilic/Hurriyet