Michael Spruhan, 52, of Windmill Copse, pleaded not guilty to arson with intent to endanger life at the opening of the trial at Chichester Crown Court on Tuesday (September 29).
He has pleaded guilty to the lesser charge of arson being reckless as to whether life was endangered.
It is alleged that Spruhan took a knife, a plastic container filled with petrol and a cigarette lighter to the Waitrose store in Storrington shortly before 3pm on April 29.
Prosecutor Jonathan Edwards said he approached the alleged victim, who is known to him, and began pouring petrol on her.
He said: “She selected some items and was at the checkout ready to pay. Mr Spruhan went up behind her and had out the container that had petrol in it, and it seems he poured it over her back onto her clothing.
“She wasn’t aware of anything happening but she felt something cold running down her sleeve and turned around. He was holding a silver object in his hand.
“She said to him ‘why?’ He said words to the effect of ‘you know why’.”
Spruhan then struck the lighter, setting his clothing alight in doing so, Mr Edwards added.
A ‘quick-thinking’ member of the public ran towards him and managed to smother the flames on Spruhan’s jumper, the jury heard.
The alleged victim suffered a small cut to her hand but was not seriously hurt.
Spruhan was arrested and detained in the store.
Mr Edwards said Spruhan had started to behave ‘a little erratically’ a few days before the incident.
He said: “A few days before April 29, Mr Spruhan started to behave a little erratically - behaviour that was of some concern to those that were close to him.
“On the day in question, it seems that he was very focused in what he intended to do.”
In subsequent police interviews, Spruhan said he visited his parents at about 2pm.
He obtained a knife from their kitchen and the plastic container from their shed.
Prior to the incident at Waitrose, Spruhan doused himself with petrol while he was outside Tesco in Storrington, the court heard.
He made his way to Waitrose where he sat on a bench outside the supermarket.
A married couple who knew Spruhan stopped to say hello but he did not respond to their greeting, the jury heard.
In police interviews, Spruhan claimed he had intended to commit suicide.
Mr Edwards said: “He said he wanted to commit suicide. He thought he had been followed by people and it got too much for him.
“He was asked whether he spilled any liquid on anyone in the store and he didn’t answer. He was asked whether any of it might have gone on (the alleged victim) and he said ‘no comment’.
“He did deny attacking or grabbing her, he said he didn’t know she would be there and he hadn’t seen her beforehand.”
Addressing Spruhan, he added: “The prosecution say you were in fact intending to endanger life, not being reckless.”
CCTV footage taken from inside the supermarket was shown in court.
The trial continues.
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