Both victims were known for opposing Assad regime and fled to Turkey’s Istanbul.
The bodies of Oroba and Hala Barakat were found in their apartment in Uskudar, a neighborhood on the Asian shore of the Bosphorus, on Sept. 21.
The Syrian suspect Ahmed Barakat, was detained in the northwestern province of Bursa after being spotted in security footage near the apartment building, a police source said.
The suspect, who was identified as a relative of the victims, will be transferred to Istanbul police for further questioning.
In February 2015, Deah Barakat, a cousin based in the U.S., was shot dead alongside with his wife and her sister in North Carolina.
Source: Anadolu Agency