Turkish police on Tuesday arrested 55 people for their alleged links to Fetullah Terrorist Organization (FETO), the group behind the 2016 defeated coup attempt, security sources said.

The police arrested 11 suspects in the capital Ankara after prosecutors issued arrest warrants for 20 suspects, as part of an investigation into terror group’s encrypted smartphone messaging app, ByLock.

18 more suspects were arrested after prosecutors in the capital issued warrants for 36 soldiers — including 25 serving soldiers — as part of an investigation into the terror group’s secret structure in the Turkish Armed Forces.

Read more: Turkey: 55 FETO-linked terror suspects arrested