A prominent Tel Aviv doctor was gunned down as he drove home from work in Ramat Gan early Tuesday morning, leaving police stumped following the fifth murder in the Tel Aviv District in one week. Prof. David Niv, 57, director of the pain clinic at Tel Aviv's Ichilov Hospital, was shot to death and his car was riddled with bullets in a attack that investigators said looked like the work of professional hit men. Witnesses saw Niv's vehicle swerve off the Aluf Sadeh Highway into a post on the road's shoulder. They alerted police and the Magen David Adom, who initially thought they were responding to a routine car crash. But when paramedics lifted Niv's corpse into the ambulance, they discovered he had been shot repeatedly in the head and upper body. Investigators now believe Niv was probably killed in a drive-by shooting. Police said they were at at a loss as to the motive for the attack, but that it was unlikely Niv was shot in a case of mistaken identity, as had initially been thought. It appeared Niv had been followed, leaving less potential for a mix-up, they said. A gag order was issued soon after the incident hit the headlines, banning the publication of all details pertaining to the investigation. At the time of the attack, the anesthesia and emergency trauma specialist was en route from Ichilov to his home in Savyon. Niv was one of the leaders in establishing International Pain Day and chairman of the European Organization for the Treatment of Pain. He had three children, aged 12, 22 and 24. Niv's murder followed a series of Tel Aviv murders that have came as a police survey ranked the district last among the country's six regions for public satisfaction. The study was presented to the senior staff of the Israel Police late Monday evening, a few hours after a 29-year-old from the North was shot in a drive-by shooting on Jaffa's Rehov Shivtei Yisrael. A passerby rushed him to the hospital, where he was listed in moderate condition. Two people were murdered in Jaffa over the weekend, and a former gangster was gunned down on Tel Aviv's Rehov Ha'aliya on Thursday. Suspects have been arrested in connection with one of those four attacks, the murder of a squatter in a Jaffa apartment. Separately, Mikhail Rosenshvili, 70, died Tuesday of wounds he sustained when he was stabbed in Tel Aviv early last week. A suspect in the stabbing broke under questioning Tuesday and offered evidence that connected him to the crime.