Detectives are re-appealing for information after a Northampton man was murdered.
The victim, 28, died after being shot with a firearm in Webb Drive, Upton, at about 9pm on Thursday.
A 22-year-old man arrested on suspicion of assisting an offender remains in police custody.
A 25-year-old woman arrested on suspicion of assisting an offender and a 23-year-old man arrested on suspicion of murder have been released under investigation pending further inquiries.
A fourth man arrested on suspicion of the possession of a firearm has been released with no further action.
Detective Superintendent Simon Cure, from the East Midlands Special Operations Unit Major Crime Team, is urging anyone who has any information that may assist the inquiry to contact the incident room on 101 as soon as possible.
He said: “This is a large-scale investigation and detectives from five forces across the East Midlands region continue to work around the clock to identify those involved and bring them to justice.
“We are working hard to establish the full circumstances that led the man’s murder and, while we have already made a number of arrests, we have several lines of inquiry and more people that we need to talk to.
“We know there are people out there who can help us piece together the events that resulted in this tragic incident.
“Any information, however small, could be really important to the investigation so if you think you can help, please get in touch.
Anyone with information is asked to call Northamptonshire Police on 101, quoting reference number 18000476859.
Alternatively, if they would prefer to remain anonymous, they can call Crimestoppers anonymously on 0800 555111.