A killer who shot dead an Indian student was "purposeful" in throwing a mop bucket of hot water over a fellow inmate, a jury heard on Monday.
CCTV footage captured the attack launched by Kiaran Stapleton at HMP Manchester where he is remanded in custody for the alleged murder of Anuj Bidve.
Stapleton threw the bucket over the head of prisoner Michael Sharp, with sugar melted in the liquid so it would stick to his victim's skin.
Kiaran Stapleton has admitted killing Anuj Bidve but has denied murder
He then carried on the assault on the Category A prison wing using billiard balls in a sock with the help of two friends from Salford armed with pool cues, Manchester Crown Court has heard.
Stapleton, 21, later told a forensic clinical psychologist in interview that he had intended to kill Sharp.
Prosecution expert Dr Adrian West said the defendant gave his account of the incident which took place earlier this year.
He said Stapleton explained that Sharp was "the one who stands out from the rest of them".
"He said he was loud, abusive, threatening and bullying people," said Dr West.
Stapleton said he came out of the shower and had seen Sharp sitting down playing chess and then "I just went and done what I done".
The defendant explained there was less than a minute between deciding what he was going to do and actually carrying it out.
Kiaran Stapleton arriving at Manchester Crown Court
"He said he knew the hot water would scald Michael Sharp and he also said that his intention was to kill him with snooker balls," said Dr West.
The CCTV footage saw Stapleton fill the bucket of hot water on a landing, walk to the two people playing on the pool table and then return to the bucket which he threw.
Dr West explained to the jury: "I saw his behaviour as purposeful and instrumental - that is a pre-determined goal of causing deliberate harm."
Stapleton, admits shooting dead random stranger Mr Bidve, 23, in the early hours of Boxing Day last year in Ordsall, Salford.
Stapleton walked over to Mr Bidve and his group of friends, asked the time, then shot Mr Bidve dead with a gun at close range.
He admits manslaughter on the grounds of diminished responsibility but denies murder.
Dr West said Stapleton told him he "felt nothing" after committing the scalding attack.
Questioning him about the killing of Mr Bidve, who was walking to the Boxing Day sales queues, the psychologist said he noted Stapleton made no reference to his victim in their first two interviews.
But Stapleton told him his name and age when asked in their third and final interview.
Dr West asked him why he selected Mr Bidve.
"He replied, 'only because he had the biggest head'," he said.
He said Stapleton went on: "I blew a hole in his head. There is nothing I can say, nothing whatsoever.
"They should have got a taxi. Things would have been different if they had got a taxi."
When asked about his own situation, Stapleton said: "My life has just turned upside down within the click of a finger."
Simon Driver, junior prosecuting counsel, asked Dr West what his opinion was on Stapleton's state of mind as he crossed the road to approach Mr Bidve.
"I consider he moved purposefully and then he purposefully asked the time because that gave him an opportunity to have a better select of those people in front of him," Dr West said.
He added that Stapleton's positioning and the way he fired the handgun was "purposeful" in its accuracy.
It has been agreed by all the clinical experts that Stapleton suffers from an anti-social personality disorder.
But Dr West said he did not think the defendant had a total lack of empathy.
"He has impaired empathy," he said. "He is still capable of being aware of the feelings and states of other people and the effect of his actions on them."
The psychologist said Stapleton would have been aware that his comment that he shot Mr Bidve because "he had the biggest head" would shock him.
He did not see Stapleton as "characteristically impulsive".
He had no history of problems with alcohol, drugs, gambling, self-harm or sexual recklessness.
The trial continues on Tuesday.
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