A university student who waited for his housemate to return home before stabbing him 30 times following a row over rent has been jailed for life.
Zack Coughlan, 23, was told to serve a minimum term of 28 years after he ambushed Jamie Collins, 21, in the garden of their home near Bristol on April 8.
He had dressed in black and donned a ski mask and gloves before lying in wait for 20 minutes for Mr Collins, who was also a robotics student.
Following the 'ferocious' murder, Coughlan cycled off on his housemate's bike to dispose of bloodstained evidence, leaving his former friend dying in an alleyway.
He went on to eat a pizza and play games online knowing Mr Collins' body was lying at the bottom of the garden waiting to be discovered.
When he finally called police eight hours later he pretended he had just found Mr Collins and was filmed sobbing in front of police officers.
He claimed cuts on his hands were from climbing trees.
The two students, both in their final-year at the University of the West of England (UWE), lived together in a property owned by Coughlan but were said to have 'different political views' and also rowed over the amount of rent Coughlan was charging Mr Collins.
Coughlan had denied murder but changed his plea to guilty on Tuesday part way through a trial at Bristol Crown Court.
Zack Coughlan, 23, was dressed all in black and wore a mask and gloves to ambush Jamie Collins, 21, in the garden of their home in Filton, South Gloucestershire
Jamie Collins was described as a' gentle soul who was averse to conflict and confrontation'
The attack was caught on CCTV installed at the house they shared, which Coughlan showed the attending police officers who initially treated him as a witness
Jailing Coughlan, Judge Mr Justice Linden said Mr Collins 'was an idealist who took an interest in the problems of the world and society'.
'His friends were unanimous in describing him as an exceptionally kind and considerate person.
'It is clear that they felt privileged to have known him and heartbroken to have lost him.'
'It comes with great shock that anyone could do what you chose to do to him,' he said.
'I'm sure you were planning to kill Collins and had been for some time.
'Your guilty plea came at a point in the trial when your conviction was inevitable.'
During the trial, Coughlan claimed he was fearful of Mr Collins, saying he had threatened to kill him and therefore he had 'no choice' but to wait for his housemate to return from university and stab him repeatedly.
Judge Linden said: 'I do not accept your evidence that he did or said anything that made you believe he would be violent towards you in any way.
'Your evidence about these conversations was at odds with other evidence about Collins, that he was a gentle soul who was averse to conflict and confrontation.'
CCTV footage of Zack Coughlan cycling on his victim's bike
CCTV footage of Zack Coughlan on campus following the killing of Jamie Collins
The court heard Coughlan had planned Mr Collins' murder for weeks, purchasing black clothing and shoes on March 27 and making internet searches on his phone such as 'what corpse looks like'.
On the day of the killing, he went into a nearby alleyway and changed into the black clothing to disguise himself.
The attack was caught on CCTV installed at the house, which Coughlan showed the attending police officers who initially treated him as a witness.
The defendant's blood had been found on Mr Collins's bike, and analysis of his mobile phone matched the killer's movements afterwards captured on CCTV.
Adam Vaitilingam KC, prosecuting, told the jury: 'This was a carefully planned and coldblooded execution.'
Coughlan dumped the bike at a nearby retail park, bought a change of clothes and threw his bloodstained clothing in a pond in carrier bags weighed down with bricks.
He returned to the house they shared in Cleve Road at about 9pm, put a pizza in the oven and played online games. At around 2am, Coughlan dialled 999 claiming he had just found Mr Collins's body crying and giving the impression he had 'just found the body of a dear friend'.
A post-mortem examination found Mr Collins had suffered more than 30 stab wounds to his front, back and neck.
Coughlan
The court has heard tensions between the two students mounted over rent as Mr Collins voiced his disdain for landlords and blamed multinational corporations for social inequality.
Coughlan suggested he was driven to kill Mr Collins, originally from Swansea, after his Left-wing views became more targeted and personal.
The judge told said his exact reasons for the murder may never be known.
He rejected assertions that Mr Collins had expressed violent sentiment about highly wealthy individuals and said he wanted to kill the defendant.
'The evidence is that he was a gentle soul,' the judge added.
'What came across from your evidence as a whole was that over time, you had become deeply upset by the realisation that Mr Collins disliked you.'
In a victim personal statement read to the court, Mr Collins' family described Coughlan's evidence as 'excruciating' and 'full of lies'.
They said his claims were an attempt to 'discredit and defame Jamie's excellent character'.
'I believe Zack Coughlan did feel threatened by Jamie,' the statement by his stepmother Lisa Collins added.
'Not because Jamie ever threatened him, but because of Zack Coughlan's own insecurities and the reality that Coughlan's friends were gravitating more towards Jamie.'
Mrs Collins added that the loss of control in the case was Coughlan's 'control over his peer group and perceived popularity'.
'Zack Coughlan knew that Jamie was a better person than him,' she said. '[He] was jealous of Jamie's integrity and strength.'
She described the devastating impact of Mr Collins' death on his family and friends, many of whom attended every day of the trial.
The court heard Mr Collins had almost completed his degree at UWE Bristol, with only two further pieces of coursework to finish before he planned to return home to Swansea at the end of April.
His family attended his graduation ceremony, where Mr Collins had accumulated enough results to be awarded a 2:1 degree.
Dan Pawson-Pounds KC, representing Coughlan, said his client had no previous convictions and friends had been 'utterly shocked' by his actions.
'He was someone who was well thought of within the peer group,' Mr Pawson-Pounds added.
The barrister referred to Coughlan's difficult background, which the defendant said in evidence included physical violence from his father and his mother often working away for her job at Apple.
Detective Chief Inspector Lucy Edgeworth said afterwards: 'Coughlan repeatedly lied in order to protect himself and finally admitted his guilt yesterday after months of denial.
'He has received a life sentence for the ferocious murder he committed and will serve a minimum of 28 years behind bars.
'The court proceedings may have concluded today, but it's important to recognise the pain Jamie's family and friends have experienced does not sadly magically disappear.
'They are a wonderful family and have shown incredible courage and dignity across the past six months, both during our investigation and sat in court every day too.
'The trial has heard a lot of distressing evidence about Jamie's final days. I hope that going forward people remember Jamie for the young man he was – a bright young student who was loved by all who were lucky to know him.'