A fresh appeal to solve the murder of a father in Highbury, north London, 15 years ago will feature on BBC Crimewatch later.
Ricky Smith, aged 25, was stabbed in the chest in Highbury Park in a seemingly unprovoked attack in 1997.
Police said new evidence links the killing to another knife attack on the same night, 3 October.
The suspect in both attacks is described as a tall, black man aged between 18 and 30.
Mr Smith, a floor fitter, had been enjoying a night out with his partner, who was the mother of his two children.
They walked together to a kebab house at around 23:40 GMT before heading home along Highbury Park.
As they walked near Hamilton Road, Mr Smith was stabbed.
The attacker made off on foot along Highbury Park turning left into Aubert Park, right into Avenell Road and right into Conewood Street, opposite the old Arsenal football ground.
A discarded baseball cap and Chicago Bulls jacket were found later in Conewood Street along with other property including a five-inch lock knife.
Police said new forensic analysis has linked the attack to the stabbing of 21-year-old Juan Marais in College Road, Harlesden, north-west London.
Mr Marais suffered serious injuries to his chest and abdomen but went on to make a full recovery.
Det Insp Colette Smyth said: "I can't believe that over the last 15 years someone out there does not know who carried out these attacks."