How could it happen that predominantly only one direction was determined?

In September 2000, 14-year-old Semiya was awakened at four in the morning. Her father is said to have had an accident. Only in the hospital does she learn that eight shots were fired at Enver Şimşek. He is in a coma and dies two days later. There are hardly any traces, but a witness claims to have accompanied Enver on a supposed drug transport. The investigation focuses on the family. When the witness's testimony is refuted, the investigation fizzles out. Over the next few years, 8 more businessmen, 7 Turks and one Greek, are murdered with the same weapon....