Mehmet Yildirim, 25, is being sought across the country, a police spokeswoman said on Friday, a day after the bloodbath in the capital's Wedding district.
It is thought at least 14 shots were fired at a 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 on Friday 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.
The BZ newspaper reported that Yildirim had harassed and threatened Feride after their marriage collapsed – and that she had even received a court order banning him from approaching her.
Police were on Friday distributing a photo of Yildirim across the country, as well as following up reported sightings of him received Thursday evening.
The shooting was particularly shocking as it happened in a busy district of the city in broad daylight and seemed to be carried out with precision. Witnesses described it as an outright execution.
“I am stunned and shocked,” said a neighbour who immediately ran to the scene after hearing shots Thursday and saw the carnage in the car. “The perpetrator simply ran away.”
Wedding is known as a centre for Berlin's Turkish-born population, which one neighbour called “socially difficult.”
Police sealed off a large area around the crime scene for several hours on Thursday as they gathered evidence and searched for the shooter.