Tel Aviv police released Dror Alperon on Thursday evening, only two days after he turned himself in.
The 18-year-old son of alleged crime boss Ya'acov Alperon is a suspect in the stabbing of apparent rival Amir Mulner during an 'underworld summit' at the beginning of January.
Dror had been on the run for over seven weeks after the incident, which took place at the Daniel Hotel in Herzliya, but turned himself in on Tuesday.
Police have passed the file to prosecutors, who will decide whether to issue indictments. Both the Alperons deny stabbing Mulner, with their lawyer saying Dror tried to extricate his father from a fight that broke out.