Kostas was arrested on December 4, 2010 in the Nea Smirni case (possession of weapons and explosives). In January 2014, he was released on bail and went on the run. In December 2014 he was sentenced in absentia to 16 years. He was rearrested with Marios Seisidis in August 2016 and sentenced to 2 years and 9 months for using forged documents and car registration plates, car theft and disobedience to authorities. On June 12, 2019, Sakkas was arrested in Thessaloniki with Giannis Dimitrakis and Dimitra Syrianou, during an expropriation of a guarded money transport that was about to refill an ATM at the university hospital AHEPA. Kostas was sentenced to 7 years and 10 months.