Four people who were arrested on suspicion of assisting an offender following a murder in St Neots have been released.
A 68-year-old man and a 64-year-old woman from Eaton Socon have been released under investigation.
A man and a woman from London have been released with no further action.
A man in his 30s arrested on suspicion of murder remains in custody at Thorpe Wood Police Station.
The four were arrested on Sunday (October 13) following the stabbing of a man in his 30s who died in Prince Close, Eaton Socon.
Despite efforts from paramedics to save him, the man died at the scene
Detective Chief Inspector Mike Branston who is investigating said the death was being treated as an isolated incident.
He said: "We will be continuing enquiries today in and around the Eaton Socon area while our investigation into the death continues."
A spokeswoman for the East of England Ambulance service said: 'We were called at 5.23pm on October 13 with reports that a man had been stabbed in Eaton Socon.
'We sent one ambulance, two ambulance officers and Magpas Air Ambulance.
'Despite our best efforts, the man died at the scene.'
A spokeswoman for the Magpas Air Ambulance said: 'The Magpas Air Ambulance advanced medical team were called to the incident yesterday evening, they landed via the Magpas Air Ambulance at 5.45pm.'
Anyone with information regarding this incident should call police on 101 quoting incident 367 of 13 October or visit www.cambs.police.uk/report. Alternatively, contact Crimestoppers, anonymously, on 0800 555111 or via www.crimestoppers-uk.org.