At least 18 lawyers including Taner Kılıç, the chairman of Amnesty International Turkey’s board, were detained on Tuesday as part of an investigation into Turkey’s Gülen group.

According to the Hürriyet daily, detainees are accused of using a smartphone application called “ByLock.”
ByLock is considered by Turkish authorities to be the top communication tool among followers of the Gülen movement, which is accused by the government of masterminding a failed coup attempt on July 15, 2016.

Turkey survived a military coup attempt on July 15 that killed over 240 people and wounded more than a thousand others. Immediately after the putsch, the Justice and Development Party (AKP) government along with President Recep Tayyip Erdoğan pinned the blame on the Gülen group.

The group denies any involvement.

Tens of thousands of civil servants, police officers and businessmen have either been dismissed or arrested for using ByLock since a failed coup attempt last July.