AYDIN, Turkey

After six relatives and the roommate of the assassin of Russia’s ambassador were arrested early Tuesday, his uncle was released on judicial control, according to security sources.

Hasan F., the uncle of slain assassin Mevlut Mert Altintas, is a former senior executive at a Fetullah Terrorist Organization (FETO) private school shut down under a FETO probe following the July 15 defeated coup, which is blamed on the group.

In addition to the uncle, earlier Altintas’ parents, sister, and two other relatives were arrested in the southwestern province of Aydin.

The relatives were taken to Aydin’s Security Directorate after questioning, said the security sources on condition of anonymity due to restrictions on speaking to the media.

His roommate in Ankara was also arrested.

On Monday, Russian Ambassador Andrey Karlov was delivering a speech at the Contemporary Arts Gallery in Ankara's central Cankaya district when Altintas opened fire, critically wounding him.

Karlov was rushed to a hospital where he was pronounced dead.

Police Special Forces killed the attacker in an operation that lasted around 15 minutes. 

FETO and its leader, the U.S.-based Fetullah Gulen, are accused by the Turkish government of being behind the bloody July 15 defeated coup and a long-running campaign to overthrow the state through infiltrating Turkish institutions, including the military, police, judiciary, and educational system.