Cemal Yavas, the brother-in-law of the former prosecutor Zekeriya Oz, who led corruption and bribery operations against the Turkish government back in 2013, was arrested.
Yavaş was detained as part of a Bursa-based investigation into the Gulen movement and was subsequently jailed pending trial, according to state-run Anadolu news agency on Tuesday.
The movement stands accused of masterminding the July 15, 2016 coup attempt in Turkey while it denies involvement.
More than 130,000 people have been detained since the summer of 2016 over Gülen ties.
Before being removed from his post, Zekeriya Öz was responsible for the investigation launched against the 2013 corruption probe that implicated cabinet ministers and the son of Turkey’s President Recep Tayyip Erdogan.
In August 2015, detention warrants were issued for Zekeriya Öz, Celal Kara and Mehmet Yüzgeç, all former prosecutors who took part in the corruption investigations. The whereabouts of Yüzgeç is unknown, while prosecutors Öz and Kara are known to live in exile.
Many of the suspects in Turkey’s 2013 corruption investigations are now suspects and witnesses in a US investigation over violating UN sanctions against Iran.