Brian Blackwell, who is beginning a life sentence for manslaughter, was a gifted academic who was nicknamed The Brains by school friends.
Brian Blackwell battered his father to death with a claw hammer
His proud parents, Sydney and Jacqueline, had hoped he would become a top surgeon.
But instead he turned on them, battering his father with a claw hammer and stabbing his mother up to 30 times.
Detectives still do not know why he carried out the brutal killings.
A sufferer of narcissistic personality disorder, which made him feel entitled to unlimited success in all areas of his life, he was a slave to his fantasy view of himself as brilliant and untouchable.
He was a pathological liar who had convinced his girlfriend Amal he was a professional tennis player with a £70,000 sponsorship deal and a place in the French Open.
Signing her up as his manager, he whisked her off on holiday to the US, wining and dining her and staying in an exclusive New York hotel.
As they travelled to San Francisco, Miami and Barbados before returning to Merseyside, Blackwell continued to act as though everything was normal.
But his web of deceit was beginning to unravel.
Blackwell had moved in with his girlfriend's parents, telling them he was locked out of his home because his parents were on holiday in Majorca.
But when he collected his A-level results from Liverpool College, the bodies of his parents - who would have been proud of his four A grades - were rotting in their own home.
BLACKWELL'S SPENDING SPREE
April 2004: He writes out a £39,000 cheque to his girlfriend despite having only 9p in his bank account
Early May 2004: He cashes in a £9,000 bond his parents invested to pay for his university education to buy his girlfriend a car.
13 May, 2004: Blackwell tries to open a bank account claiming he is a professional tennis player earning £45,000-a-year and about to play in the French Open.
Late June 2004: Blackwell's mother calls at a local bank to say she is concerned about her son's behaviour.
July 25 (the day of the killing): He books a 1st class business flight from Manchester to New York, using his father's credit card again.
26 July: Blackwell pays £3,900 for a three night stay at the Plaza in New York.
Between 26 July and 12 August: In total Blackwell spends £30,000 during a two week trip around the US and Barbados.
Police were called to the family's three-bedroomed bungalow in leafy Melling on 5 September 2004 after a neighbour reported a strong smell.
Inside, they found Mr Blackwell's decomposing body in an armchair in the living room.
Mrs Blackwell's body had been dragged into the bathroom. She had been stabbed after witnessing her son batter her husband to death.
Neighbours in Melling were shocked by the killings.
Margaret Smith, 73, described Blackwell as a "lovely, quiet lad", adding that as a youngster he had not been allowed to play with many other children.
And 75-year-old Tommy Sheldon, a retired Royal Navy seaman, said he was a "very clever" lad who played tennis at the local club and studied hard.
"His mother was inclined to be strict with him," he said.
Police had originally thought Blackwell's parents may have pushed him too far in his studies, but this was eventually discounted.
Det Insp Geoff Williams, of Merseyside Police, said: "His mother and father were very ambitious for him but there was nothing to suggest they had pushed him down a certain road.
Jacqueline Blackwell was stabbed up to 30 times by her son
"It actually seems he found his exams and studies quite easy.
"We don't know the sequence of events that happened in that house that enraged young Brian and left him in a position when he felt he had to kill his parents.
"Whether it was for a financial reason at this point is pure speculation."
Blackwell had applied for 13 credit cards using false information and applied for numerous loans to fund his lifestyle.
His mother, who was aware of the situation, had been to the local bank to discuss his problem.
Argument with father
During police interviews, Blackwell told detectives he had been hanging pictures in his bedroom and had a hammer.
"His mother and father had been out having an evening meal and had returned home," Det Insp Williams said.
"After a few drinks there was an argument between Brian and his father.
"It resulted in a fracas between them in the living room."
A team of psychiatrists were called in to analyse Blackwell and agreed unanimously that he had a narcissistic personality disorder, which results in the sufferer being obsessed with the fantasy of unlimited success, power, brilliance and ideal love and beauty.