A university student lay in wait for his housemate to return home before stabbing him 30 times, a murder trial has been told.

Zack Coughlan, 23, dressed all in black and wore a mask and gloves to ambush Jamie Collins, 21, in the garden of their home near the University of West England in Bristol, where both studied robotics.

Collins was attacked shortly before 6pm on 8 April after returning from campus on his bike, Bristol crown court heard.

Coughlan then allegedly cycled away on the bike, dumped it at a nearby retail park, bought a change of clothes and threw his bloodstained clothing into a pond.

He returned home to the house they shared in Filton, south Gloucestershire, at about 9pm, put a pizza in the oven and did some online gaming with friends, the court was told.

Adam Vaitilingam KC, prosecuting, said: “A few hours later he decided it was time to call the police and pretend that he had just found his friend’s body in the garden.

“At about 2am – eight hours later – the defendant called 999. He said that his friend had been stabbed. They told him to do CPR until paramedics arrived and he told them that he was.”

He told police he had noticed the back gate was open, went outside and found Collins’s body.

The court heard the attack was caught on CCTV installed at the house, which Coughlan showed officers who initially treated him as a witness.

Coughlan had injuries to his hands but he said he had hurt himself when he fell while climbing trees.

Vaitilingam said that as evidence against Coughlan mounted, he went from being a witness to a suspect. He now accepted he had killed Collins but denied murder. He said he “lost his self-control” when he carried out the attack, the barrister said.

The jury was told that Coughlan and Collins were both final year students and lived together in a house owned by the defendant.

Vaitilingam said there had been disagreements between the pair about paying rent and whether Coughlan was charging too much, but they appeared to have been resolved.

“There was nothing that any friends were aware of that seemed to be a significant problem,” he said. They hung out together both in person and online, they did gaming together, they went out together, entirely normal student life.”

The trial continues.