The assassin who shot dead Russian Ambassador Andrey Karlov in Ankara on Monday was in touch with eight people, including seven police officers through the Bylock app, sources in the Ankara Public Prosecutor's Office and police told.

The ByLock messaging app is said to be linked to the July 15 defeated coup.

Mevlut Mert Altintas, the off-duty policeman who murdered Karlov, had used the app to stay in touch with eight people, including seven police officers who had been dismissed after the coup bid, the sources, who wished to stay anonymous due to restrictions on talking to the media, said Thursday.

The new information about the killer came to the surface when a special investigation team, established under the supervision of the prosecutor’s office, carried out an examination of the phone line registered under Altintas’ name.

The eight people, including a police captain, a deputy police chief, five police officers and a businessman in Denizli had worked with Altintas in the same police branch, the sources added.

Karlov died on Monday after being shot multiple times at an art exhibition in Ankara. He was delivering a speech when the 22-year-old Turkish assailant opened fire. Altintas was later gunned down in an exchange of fire with security personnel.