Fighting back tears, Kim Kensett, 40, said: "I had to watch him die. You never expect to see the death of one of your own children. It isn't something you're supposed to see."
Jay's site foreman father, John, also 40, cradled his son, pleading "fight for your life" as others tried to revive him.
The 16-year-old Marina High School pupil, a talented boxer and footballer, was stabbed in the back with a carving knife after an argument with a man and a woman in Whitehawk Way, Whitehawk, Brighton, just before midnight on Friday.
Pal Gavin Dawes, 15, of Pleyden Close, Whitehawk, spoke of the horrifying moment when Jay fell dying.
"He span around twice. He nearly choked and said 'I've been stabbed' and then fell over on the floor.
"I took Jay's mobile out of his pocket and rang for an ambulance."
After the stabbing, Jay's parents were alerted by his friends, who ran 100 yards to their home in nearby Pulborough Close to raise the alarm.
Astatement issued by the Kensett family yesterday afternoon said: "The whole family are totally devastated by what has happened.
"We want to thank the people who tried to save Jay and everyone who has left flowers.
"If anyone heard or saw anything on Friday night or has any information which can help the police, please come forward.
"We want whoever is responsible stopped from doing this to anybody else's son."
Murder squad detectives recovered a knife at the scene and later arrested a 19-year-old woman, and two men, aged 27 and 30, who were being questioned at Brighton's John Street police station.
Jay's grandmother, Irene Kensett, from Sompting, near Worthing, said: "His parents are in an awful state. They had to formally identify the body on Saturday morning."
The Taylor family, who live opposite the scene of the stabbing, told how they tried to save Jay.
Ernest Taylor, 40, said: "It was an horrific scene. There were youngsters screaming and shouting and the lad was covered in blood.
"At first I couldn't see the injury. Then I put him the recovery position and it was obvious the wound was in his back.
"I lifted up his shirt and jacket and the knife was still in him. It looked like a long carving knife. I took my shirt off and used it to stem the blood."
His wife, Bernice, 35, said: "His father was saying 'come on Jay, fight it', but then he seemed to realise how serious it was and shook his head in his hands and asked 'he's dead isn't he?'."
Son Mark, 17, a student at Brighton College of Technology, said: "I gave him mouth-to-mouth and eventually the police turned up and an officer took over.
"I couldn't find a pulse but the policeman had some kind of tube which he put in his mouth to help him breathe."
Jay was taken to the Royal Sussex County Hospital, Brighton, where doctors tried in vain to save him.
Jay had three brothers, Dean, 19, soldier Ross, 18, and Tyrone, 13, and a sister Jayde, 11.
Converted for the new archive on 30 June 2000. Some images and formatting may have been lost in the conversion.
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