Tipu Sultan, 32, a father-of-two, was shot at close range outside Herbs n Spice Kitchen, Lake Avenue, South Shields, on 7 April.
Northumbria Police confirmed it had arrested two men aged 47 and 24, and a woman, 27, on suspicion of murder.
A 44-year-old woman has been arrested on suspicion of assisting an offender.
A reconstruction of the killing was broadcast on the BBC's Crimewatch programme, which police said resulted in a number of fresh leads.
Four people have been arrested in connection with the murder of a man who was shot dead outside a takeaway.