A volunteer with Norwich's SOS bus saw a man 'staring intently' at a 48-year-old father-of-two shortly before he was murdered, a court heard.
The victim of a fatal stabbing in Norwich city centre was subjected to "non-stop blows" from a knife-wielding attacker, a court heard.
Father-of-two David Hastings was stabbed to death in what prosecutors say was an unprovoked attack near Rose Lane car park on June 23 last year.
Rolands Heinbergs, 23, of HMP Belmarsh, is on trial at Norwich Crown Court having pleaded not guilty to the 48-year-old's murder.
Prosecution witness Jacob Conneely told a jury on Thursday how he saw the attacker repeatedly stab Mr Hastings near the car park's toilets.
He said: "I can remember a lady shouting or screaming.
"At first I saw the gentleman punching the victim and then I saw the blade [reflection] catch in the street light."
Mr Conneely said he initially thought the attacker had a "weird punch" as he was swinging his arm from the side.
He said as the victim was about three quarters of the way across the road, the attacker made a "downward swipe" motion towards his neck.
"It was non-stop blows from one side of the road to the other," Mr Conneely said. "When I saw the downwards swipe I knew he was gone."
He told the jury how he ran to Prince of Wales Road to alert the police.
Prior to the attack, Mr Conneely was part of a group of friends who used the car park's toilets at the same time as Mr Hastings and his partner.
He said he saw the attacker waiting near the victim, but said there was no talking between the pair.
"The atmosphere felt weird at first," Mr Conneely said. "I felt a bit on edge, but when we started speaking to the gentleman [Mr Hastings] I felt a bit more relaxed."
He estimated that the blade used in the attack was about 10 inches in length and two inches wide.
The court also heard evidence from SOS bus volunteer Beth Williams.
She told the jury she was working with the service on Prince of Wales Road on the night of the attack.
She recalled seeing a man who was "fixated" on Mr Hastings and his friend as they were sat outside a Subway shop during the evening of June 22.
Miss Williams, who knew the victim by his first name, said: "There was a man, sitting in the bus stop, and there was something not right. This was about 11.30pm.
"He was staring intently at Taff [Mr Hastings's friend] and David.
"He was fixated in that direction which I think is what flagged it up [to me]. He was intensely focused."
Miss Williams said the man, who was dressed in dark clothing and carrying a dark backpack, glanced towards her and then "abruptly" got up and walked away.
She told the jury that later in the evening she heard shouting and ran up to Rose Lane where a man was "bleeding badly".
Earlier in the trial, the jury was told how Mr Hastings was suffered 13 stab wounds in an attack shortly after midnight.
CCTV footage played in court shows the victim escorting his girlfriend to the ground floor toilets of the Rose Lane car park.
A man in a dark hooded top and carrying a backpack can be seen to follow the couple and wait nearby.
As Mr Hastings's girlfriend exits the toilets, the man reaches into his pocket for a knife and carries out the attack.
Prosecutor Wayne Cleaver said Mr Hastings was in "the wrong place at the wrong time" and was a "complete stranger" to the attacker.
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.
The trial continues.
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