Three people have been arrested in connection with the murder of 17-year-old Louis-Ryan Menezes who was stabbed last Friday in Northampton.
A 16-year-old boy and a 34-year-old woman from Northampton and a 37-year-old man from London were arrested on Tuesday night and are in police custody.
The development follows the release of two teenage boys and a 38-year-old man without charge on Saturday after they were detained in connection with the murder.
Police said house-to-house inquiries in the area provided them with fresh lines of inquiry following their release.
The investigation, led by the East Midlands special operations unit, includes more than 40 detectives.
Louis-Ryan was pronounced dead after being taken to Northampton General Hospital following the incident at Drayton Walk, Kingsthorpe, Northampton, at 6.15pm on Friday.
Officers want to speak to anyone who was in the Drayton Walk area of St David’s between 6pm and 7pm on Friday May 25, or in or around Eastern Avenue North or the shopping parade in Newnham Road.
Anyone with information is asked to call police on 101 or Crimestoppers, in confidence, on 0800 555111.