The officer and Yassine Atar (pictured) are believed to have been in contact before the attacks. The officer was detained on Monday and accused of violating the police code of conduct and corruption. He is thought to have leaked confidential information to people under scrutiny in a terrorism investigation. The officer is believed to have been in contact with Yassine Atar, the brother of Oussama Atar, who is suspected of organising the Brussels attacks on the metro and the airport via WhatsApp. The Atar Brothers are nephews of the El Bakraoui Brothers, who blew themselves up during the metro and airport attacks.

Yassine Atar is Oussama Atar's younger brother. He's been in custody since he was detained five days after the attacks. His exact role is unclear, though he is believed to be a pivotal figure.