A man who watched burglars raiding his family home over a doorbell cam rushed home and stabbed one of them to death, a court has heard.
Karl Townsend, 32, and his half-brother, Jamie Cunningham, 23, are accused of arming themselves with knives after being alerted to the break-in at his property in Merseyside, through a Ring doorbell camera.
Townsend shouted at three intruders to get out of his home, before stabbing Jordan Brophy in the face and head, leaving a broken blade embedded in his brain, Liverpool Crown Court heard on Monday.
The court was told Townsend and Cunningham left the scene but returned a short time later, when Townsend stabbed Brophy in his jugular vein.
Townsend and Cunningham both deny murder and possessing a bladed article.
At the opening of their trial, Richard Pratt, QC, prosecuting, said: "The prosecution case is that this was not a case of a householder in a state of fear and panic, reacting in a moment of terror to what he believed to be real danger.
"This was a brutal and ruthless killing, whether it be out of revenge or punishment, of a defenceless man."
The court heard Townsend lived in Beechwood Avenue with his partner and their child.
On the evening of 29 October last year, his girlfriend was out walking with their child and dog, while he was at his parents' house in nearby Penman Crescent, where Cunningham also lived.
Pratt said Brophy was "engaged in burglary" with others at Townsend's home.
He said the property had a CCTV security system that included a Ring doorbell, meaning cameras are activated and the householder is notified via his or her mobile phone.
Townsend left his home at 6.26pm in his Mercedes GLA car, the court heard. About five minutes later, three cars were seen travelling along Beechwood Avenue, which Pratt said "appeared to be in convoy".
He said one or more of those cars was carrying Brophy and "three unknown associates" to carry out "a determined and apparently targeted attack" at Townsend's house.
Three of them broke in through a side door, while the fourth waited in another Mercedes parked nearby.
Pratt said Townsend and Cunningham "hurriedly" made their way to the house after the doorbell camera alert went off and they had "armed themselves with large knives".
He said: "As they entered, Karl Townsend can be heard to shout to the burglars to get out of his house or he'll do something to them with the knife he's carrying.
"What actually happened inside the house is not captured by any camera. But 25 seconds after the two defendants enter into the property, the burglars were seen to emerge from the back door, and Jordan Brophy was complaining that he could not see, and he had some sort of injury to his face in the region of his eye.
"There was a reason he could not see. Karl Townsend had stabbed him twice to the face and head. The stabbing actions were so severe that they smashed their way through bone and cartilage and in one case severed the optic nerve and entered the brain.
"Such was the thrusting action that the knife broke not once but twice, leaving broken parts of the blade embedded in the skull and brain of Jordan Brophy."
The prosecutor said: "Burglary is of course a despicable crime, and can cause misery to those who come back to find their homes have been violated. It must be even worse to find the perpetrators still in the house.
"But that cannot begin to justify this level of severe violence. But what is worse, is that even after he had stabbed Jordan Brophy with such force as to leave him with only the remnants of a broken knife in his hand, Karl Townsend had not finished."
The court heard he and his half-brother returned to the scene. Pratt said a car carrying Townsend and Cunningham returned within around a minute and crashed into a wall outside another house in the street.
Pratt said Townsend stabbed Brophy repeatedly and the knife entered about 4.5cm deep into Mr Brophy's neck and his jugular vein, causing "catastrophic blood loss".
He said: "According to the pathologist who carried out the post-mortem examination, Jordan Brophy would have died in time from the brain injuries inflicted inside the house, but the one to the jugular vein killed him almost instantaneously."
Pratt said Townsend caused Brophy's death but that Cunningham "bears responsibility too".
The prosecutor said Cunningham "plainly and intentionally assisted and encouraged" his half-brother, intending that he would either kill Mr Brophy or cause him really serious harm.
The trial continues.