Atalay Filiz was born on June 2, 1986, in Bandırma, Balıkesir, Turkey. His father was an officer in the Turkish Air Force, and after retiring from the military, he became a pilot for Turkish Airlines.

Filiz attended Galatasaray High School in Istanbul, which is known as one of the best high schools in Turkey. He graduated with honors. His teachers praised his intelligence, stating that he was so capable that he would be able to survive in challenging situations on his own. In 2005, he took the OSS exam, a test for higher education in Turkey. However, he did not aim to pass the exam. Instead, he intentionally answered some questions incorrectly to pursue his goal of studying abroad.

After high school, Filiz went to France to study biology at the University of Paris-Sud. During his time in France, he did not attend classes or take exams. Financial difficulties prevented him from completing his studies. In 2010, he returned to Turkey and told his family he planned to pursue a doctorate degree in Ankara. However, later investigations revealed that he was never registered for a doctorate program.

In December 2011, Olga Seregina, a Russian woman living in Paris, disappeared under mysterious circumstances. She was last seen after agreeing to meet Atalay Filiz for coffee. Olga had emailed a friend the night before, stating she would meet someone important. After December 17, 2011, no one heard from her again. Authorities suspected Filiz, but he denied any involvement. As the investigation continued, it became clear that he had become obsessed with Olga, leading to concerns from her friends and family.

On May 27, 2016, Filiz is believed to have murdered Göktuğ Demirarslan and his girlfriend Elena Radchikova. Filiz felt that they blamed him for Olga's disappearance. He had been sending them aggressive emails after they cut off contact with him. Using a payphone, he lured Göktuğ to a location where he could commit the crime. He ambushed them as they returned home, shooting both at close range.

The killings were particularly brutal. Göktuğ's remains were scattered across a wide area due to the force of the bullets. After the murders, Filiz fled the scene and evaded capture for an extended period. He even hid a tracking device in Göktuğ's car and attempted to follow the couple during their vacation.

In June 2016, Filiz murdered Fatma Kayıkçı, a woman who had welcomed him into her home. He became paranoid that she would expose his past crimes. In his confession, Filiz admitted to stabbing her multiple times. He later disposed of her body in a nearby area.

After the murder of Fatma, Filiz went on the run, staying in various locations while evading police. His time as a fugitive ended on June 12, 2016, when he was arrested. Following his capture, authorities discovered a trove of incriminating evidence, including fake IDs and weapons, in his possession.

Filiz faced trial for his actions. Initially, he was charged with homicide for the three murders. During his court appearance, he acknowledged his guilt but claimed he was not stealing from any of the victims. He was held in Silivri Prison while awaiting his trial outcome. Investigations into his mental health revealed that he was stable, further complicating his defense.