Various diagrams and a map of Brussels airport hit by terrorists on Tuesday were found on computers and USB sticks at an apartment located at Pagrati area in Athens, Greece, as TV station SKAI reported.

The apartment was used as a hideout of the ringleader of the Paris terror attacks, Abdelhamid Abaaoud, until January 2015.

According to SKAI, all the evidence found in ringleader’s apartment, as well as what police had found in another apartment at Sepolia area in Athens, were sent to Belgian authorities, which identified the DNA of ISIS fighter, who had disappeared from Greece, on their own responsibility.

Belgian authorities’ actions raise many concerns, since on January 2, 2015 they had requested Greek authorities to investigate a person using a phone device located at Pagrati to coordinate the actions of jihadists’ core in Verviers, even though they knew that this person was Abaaoud.

Until January 15, when Belgian authorities decided to conduct an operation, the terrorist had plenty of time to hide his tracks.

Greek authorities found Abaaoud’s hideout on January, 17-19 and arrested two people, one of Algerian origin and one of Syrian origin.

Ten days later, Greek authorities were informed that the Syrian was a French national and it was known that he was recruiting jihadists in Europe.

Abdelhamid Abaaoud was accused of recruiting Belgian jihadists and convicted by Brussels’ court in July after departing for Syria to 20 years in prison.

In 2014 he was on the front pages of Belgian media for kidnapping his 13-year-old brother, “the youngest jihadist in the world”, and taking him to Syria. His father, Omar Abaaoud, had filed a lawsuit against him for kidnapping.