The mother of a man who was stabbed to death said she believes someone locally is "hiding something" as his murder remains unsolved.
Shane Fox, 26, died from a knife wound to the chest in Nest Farm Crescent on the Hemmingwell Estate, Wellingborough, at about 02:00 GMT on 1 December.
A 22-year-old man was arrested and remains under investigation.
In a video released by Northamptonshire Police, Caroline Fox said "somebody on this estate knows something".
"Someone's hiding something because there's no way that someone could stab someone and act normal - not in my book anyway," she said.
Police described the suspect as a black man in his 20s, wearing a dark-coloured puffa-style jacket with horizontal stitching.
The force also said they wanted to trace a man seen "shouting aggressively" towards Mr Fox's house at about 21:00 on 30 November.
He was described as white, about 5ft 7in to 5ft 8in, with a slim build and a bald head.
At the time of the attack Mr Fox was with another man who was also stabbed, but was not seriously injured.
Mrs Fox said: "Our whole world has been turned upside down. We've lost Shane. Nothing is ever going to be the same again.
"Anything [the public] might think is pointless - let the police decide if it's pointless or not."