A university robotics student who stabbed his housemate 30 times in a 'carefully planned and cold-blooded execution' has pleaded guilty to murder.
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.
Bristol Crown Court heard Mr Collins was stabbed repeatedly and Coughlan left him dying in the alleyway as he cycled away on his housemate's bike.
The pair were said to have rowed over the amount of rent Coughlan was charging Mr Collins, who was also a robotics student.
A murder trial was underway at Bristol Crown Court because Coughlan initially denied the charge, although he did admit killing Collins.
However, Coughlan, of Filton, has now changed his plea to guilty and will be sentenced on Wednesday morning.
Mr Collins was attacked shortly before 6pm on April 8 this year after cycling home from the UWE Bristol where he was studying robotics alongside his killer.
Adam Vaitilingam KC, prosecuting, told the jury: 'This was a carefully planned and cold-blooded execution.'
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
Bristol Crown Court heard Mr Collins (pictured) was stabbed repeatedly and Coughlan left him dying in the alleyway as he cycled away on his housemate's bike
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
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 did some online gaming with friends.
At around 2am, Coughlan dialled 999 claiming he had just found Mr Collins's body in the rear garden.
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.
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.
He also had injuries to his hands, and he told people who saw him bleeding that he had been climbing trees and had fallen and hurt himself.
After the murder, Coughlan told a university friend he wanted to hold a memorial for his housemate.
Following his change in plea, Mr Justice Linden told the jury: 'You will have just heard that the defendant has changed his plea to the indictment to guilty.
'That means that he now admits the charge of murder.'
Coughlan and Mr Collins, originally from Swansea, were both final-year students and lived together in a £300,000 three-bedroom house owned by the defendant.
Mr Collins (pictured) was left to die in an alleyway for eight hours
The defendant is half Danish and grew up with his family in Cork, Ireland, before moving to Bristol to study robotics at the age of 19.
He previously told jurors he stabbed Collins because he 'had no choice' and feared Mr Collins would kill him.
Senior Investigating Officer Lucy Edgeworth said: 'Coughlan made out he was scared of Jamie and said he lost control out of fear for his life.
'Not a single shred of evidence to support that claim was found during our investigation and it was not an account he shared with police during three interviews after he was arrested.
'Such behaviour would have been grossly out-of-character for Jamie, but more crucially the sequence of events does not stack up to scrutiny.
'According to Coughlan, Jamie threatened him twice and made him feel so scared for his life that he had to take matters into his own hands.
'However, the third housemate heard nothing, which seems unlikely if Coughlan was telling the truth.
'In the hours before the murder, Coughlan was hanging out in the living room while Jamie was still home. No one would do that if they thought there was someone under their roof who wanted to seriously harm them.
'In court, Coughlan admitted to lying in the hours and days after the murder. Yet he still tried to turn the tables and blame Jamie for the vicious murder he committed, when Jamie is tragically no longer able to defend his name.
'Coughlan lied continuously to protect himself – whether it be to police or his friends about what happened – and the jury unanimously saw through the unevidenced claims he made in court.'
In a statement released after Mr Collins's death, his family said: 'Our Jamie was a bright, kind, gentle and unassuming young man with his whole life ahead of him.
'He was looking forward to finishing his uni journey and planning to come home to us in Swansea in just a few weeks' time.
'We know he was heading for a hugely successful future following his engineering and robotics degree.'