A detective told a jury how a knife believed to have been involved in a fatal stabbing, in Norwich, had been bought from Morrisons supermarket.
Father-of-two David Hastings was stabbed to death in what the prosecution say was an unprovoked attack near Rose Lane car park on June 23, last year.
Rolands Heinbergs. 23, is on trial at Norwich Crown Court after pleading not guilty to the 48-year-old's murder.
The jury heard how after the stabbing the attacker was seen to run off towards Mountergate.
Detectives made a thorough search of the area and found packaging from a kitchen knife bought from Morrisons in a rubbish bin, near to Baltic House.
Det Con Hazel Flower said that with the information gained from the packaging she had been tasked to buy an identical knife from the supermarket and said she had bought the knife for £4.
However in his opening, prosecutor Wayne Cleaver said that evidence from a pathologist, who examined Mr Hastings wounds suggested the kitchen knife was not used and raised the question of Heinsbergs being armed with two knives that night.
Earlier the trial heard how Mr Hastings suffered 13 stab wounds in the attack which happened shortly after midnight.
Mr Hastings, formerly of Long Row, Norwich, suffered stab wounds to his heart, lung, liver and carotid artery.
He was taken to the Norfolk and Norwich University Hospital, but died from his injuries.
Prosecutor Wayne Cleaver said that Mr Hastings was a complete stranger to the alleged attacker and said Mr Hastings was in the wrong place at the wrong time.
The trial continues.
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