We're now hearing more about Prosper's time at school, where he was described as a "geeky" boy who was into computers.

Cray says Prosper would complain when people tried to talk to him and "invade his personal space".

A teacher recalled how he showed "social awkwardness" and "lack of interest in interacting with others".

By February 2023, there were concerns about Prosper's mental health and in March that year, he dropped out of school and his A-level studies.

"Whilst unemployed his life seemed to revolve around going to the gym and spending time alone on his computers," Cray says.

Summarising the prosecution's case, Cray says Prosper obtained the gun by "a clever fraud".

Prosper murdered his mum and two younger siblings, but he was "prevented by chance and circumstance alone" from carrying out the school shooting.

Cray says he wanted to achieve international notoriety as a mass murderer.

Cray says Prosper wanted to kill his family in their sleep and then remain in the flat until about 08:30.

"He would then have gone to St Joseph’s and forced entry to the early years’ assembly, hoping to kill over 30 early years pupils, and two teachers, before killing himself," Cray continues.

He says the plan was disrupted when Prosper's family "realised something was terribly wrong and challenged him".

Instead of the family dying in their sleep, there was instead an "extended, violent struggle".

Cray adds: "The defendant knew that the noise must have led to the police being called.

"As a result, he had to leave the flat at 05:30, about three hours earlier than he had bargained for."

We're now hearing how Prosper got hold of a shotgun the day before the murders.

He did so by "deceiving" a private seller, using a "high quality forgery" of a shotgun licence, Cray says.

"This included learning enough background detail so that he could sound like someone with a legitimate interest in owning a shotgun for clay pigeon shooting," he continues.

"In truth, of course, he obtained the gun as a murder weapon which he used to kill his family and which he was intending to use at the primary school."

The court has briefly been told how a psychiatrist believes Prosper has "all the symptoms" of Autism Spectrum Disorder (ASD).

Both his parents and teachers suspected he might have ASD, but he remained undiagnosed.

The psychiatrist found Prosper had an "extreme lack" of empathy and remorse - something that could not be explained by ASD alone.

Cray is now returning to the events of 13 September.

He says between 07:53 and 07:55, Prosper was seen on several residential cameras walking along Bramingham Road – which is near to Leabank.

Cray explains Prosper had been hiding for two hours and the air was filled with the sound of sirens.

Prosper was arrested after putting his hand up to gesture at a passing police car.

The officers pulled over and found he was armed with a knife in his trouser pocket.

Prosper then walked them to bushes where he had left a bag containing the loaded shotgun and cartridges.

We’re now getting more details of that harrowing note written by Prosper.

It contained a diagram of the early years classroom at St Joseph’s and an arrow pointing to a second classroom.

Beside the first classroom he had written "kill all", Cray says.

The prosecutor says Prosper purposely chose Friday the 13th to carry out his attacks and that he wanted to gain "infamy" by doing so.

"He was not just play acting or fantasising," Cray adds.

"The evidence suggests that what drove him on most was the desire to be famous or infamous as a mass killer.

"This was killing for the sake of killing."

“The defendant’s main wish was to achieve lasting notoriety as a mass killer,” Cray reveals.

He says Prosper wanted to "imitate and even surpass" other mass killers around the world.

The court is told Prosper extensively researched shootings in the US, Norway, Australia and New Zealand.

Cray continues: “He understood his plans, if realised, would bring about the greatest number of deaths in a school or other mass shooting in the United Kingdom and possibly even in the United States of America.”

Police found a note, written by Prosper, that read this would be “one of the biggest events ever”.

Cray says the police investigation that followed revealed murdering his family was Prosper’s "first step in an even more shocking mass killing".

That plan was to kill “at least 30 of the youngest pupils and two of their teachers” at St Joseph’s Catholic Primary School in Luton, the prosecutor adds.

Prosper attended this school as a child – and his victims would have been four or five years old.

“He had been preparing these killings for months. His planning was cold, deliberate and without sympathy or emotion towards the actual victims or potential victims,” Cray adds.

Police officers arrived at the scene at 05:50, having been called by a neighbour who heard a disturbance from the family’s flat.

Cray says officers forced entry and found the victims’ lifeless bodies.

Juliana Falcon and Kyle Prosper were discovered in the property’s hallway.

Cray says Giselle Prosper was found beneath a dining table in the living room, as if she had been "trying to hide" there.

Nicola Haseler
BBC News

Prosper showed no reaction as he listened to the prosecutor describing how he killed his family.

The triple murderer continues to look down at the file he's holding.

Opening the case, prosecutor Timothy Cray KC says the murders took place inside the family home – a flat called Leabank in the Marsh Farm area of Luton.

All three were gunned down by Prosper, who was using a shotgun, at about 05:00(BST) on Friday, 13 September last year. They each died from gunshot wounds to the head.

Cray says Kyle Prosper's death was particularly "shocking" as he had sustained more than 100 knife wounds.

CCTV footage captured Prosper leaving the property at 05:33, Cray says. He was then seen wearing a black hoodie by a resident leaving for work.

Nicola Haseler
BBC News

The courtroom is packed here in Luton. Prosper's family are here in the public gallery.

Sat in the front row is his dad, Ray Prosper.

Prosper has been brought into the dock, wearing a dark T-shirt. He's looking down at a file of evidence.

He hasn't made eye contact with his family.

After a slight delay, journalists have been allowed to enter the courtroom here at Luton Crown Court.

The judge, Mrs Justice Cheema-Grubb, has taken her seat and Prosper is being brought into the dock.

Stick with us as we bring you the latest.

The tribute issued through Bedfordshire Police has been the only statement the Prosper family have made since the killings.

However, Prosper's dad offered support to him during his first court hearing in September.

Ray Prosper shouted: "I still love you, son. It's not your fault, OK?" and then wept.

Image source, YouTube

Nicholas Prosper is currently 19 years old. At the time of the attacks, he lived with his family in the Marsh Farm area of Luton.

He had attended the Cardinal Newman Catholic School in the town.

It is not known whether there were any behavioural concerns about him, whether he received any additional support or whether he was on an education, health and care plan.

Prosper had no history with his local mental health trust.

Police stopped him before he could commit a school shooting in the aftermath of the murders.

Image source, Telltale Games

During their investigations, police learned Prosper had an apparent growing obsession with a child video game character called Clementine.

She featured in a video game inspired by The Walking Dead, a series set in the wake of a zombie apocalypse.

In a video posted after the killings, Prosper told the camera: "I am the chosen one; chosen by Clementine. I am guided as Christians are guided by Jesus Christ."

Brian Farmer
Reporting from Luton Crown Court

There are more than a dozen journalists waiting outside Court Five at Luton Crown Court this morning.

The deaths of Juliana Falcon, Kyle Prosper and Giselle Prosper last September shocked the local community, as well as those who subsequently learned about what happened.

Today, their relative will be sentenced for murdering them.

Prosper's internet history was analysed by the BBC after he admitted the murders.

One website he seemed to be a frequent user of featured videos of people's final moments.

Bereaved families have this week called for the "vile" site to be shut down.

Eerily, he also appeared to have an interest in mass shootings, including the 1999 Columbine High School massacre.

He was banned from one website after making comments of a pro-paedophile nature, and even admitted to having watched a notorious child sexual abuse video.

However, he has not been charged in relation to possessing any such material.

Image source, Sam Read/BBC

Hazel Simmons, Labour leader of Luton Borough Council, said Prosper's school shooting plan was "extremely shocking, distressing and upsetting".

"We don't underestimate the emotional difficulty this news will have on children, staff, parents and carers across our school community," she said previously.

Simmons said the town's schools had "robust systems in place" to keep people safe, with security "constantly reviewed and monitored".

"We will be asking schools to further review security measures in light of what came out [from Prosper]," she added.

Maureen Murphy, head teacher of St Joseph's Catholic Primary School, said the community was "devastated" to hear of the murders.

"We were very shocked to learn that St Joseph's was an intended target in this incident," she added.

"However, we would like to reassure our parents and carers that there is no threat to the school."