Police had launched a massive nationwide manhunt for Mehmet Yildirim, 25, after he allegedly killed his ex-wife's mother and sister in a shooting bloodbath in the capital's Wedding district last Thursday.
Special operations police officers caught Yildirim on Sunday night about 11:45 pm, near the Grenzallee U-Bahn station in the capital's southern Neukölln district, a police spokesman said.
Yildirim had been walking to the U-Bahn stop when he was arrested, offering no resistance. The police spokesman said intensive investigations had led to the arrest.
Yildirim is thought to have fired at least 14 shots into a parked car in which Yildirim's 24-year-old former wife was sitting with her 45-year-old mother and 22-year-old sister as well as two men aged 27 and 24.
Yildirim's former wife, named by the city's tabloid newspaper BZ as Feride, was unharmed in the attack, but her mother died at the scene, while her sister died of her injuries later in hospital. The 27-year-old man who was hit in the head by a bullet, was operated on Thursday night and remains in a critical condition. The 24-year-old man wasn't hurt.