‘He was scared for his life’: Teenager who killed Mason Miller in Northampton park 'acted in self-defence', court hears

The three defendants accused over the death of 20-year-old Mason Miller have outlined their defence cases at Northampton Crown Court on Monday, November 9.

Mason died after being stabbed at Briar Hill Skate Park, in Northampton, on Wednesday, February 18, 2026.

The trial concerns an alleged two-against-two machete fight involving Mason and three defendants, aged 16, 17 and 18. All three deny murder and manslaughter.

The court previously heard that the incident happened at around 3.30pm on February 18. The prosecution alleges the 16-year-old and 17-year-old were on one side, with Mason and the 18-year-old on the other.

Prosecutor Mark Haywood KC told the jury that all four shared a ‘common purpose’ to fight with machetes, with each side intending to kill or cause really serious harm.

Mason was stabbed during the confrontation and died from his injuries. The 18-year-old also suffered life-threatening injuries but survived after urgent medical treatment.

An eyewitness, who was buying drugs from the 16-year-old and 17-year-old at the park, told the court that all four had drawn large machete-style knives and were fighting. He described them as "going at it with machetes".

The prosecution says this was not an act of self-defence, but a fight in which all four were prepared to use serious violence.

The jury has also heard about an earlier machete incident in St James on April 6, 2025, involving the 16-year-old and 18-year-old defendants. The prosecution alleges the 16-year-old struck the 18-ear-old defendant on the head with a machete, leaving him with a fractured skull and a serious neck wound. He was taken to hospital by air ambulance.

The 16-year-old denies wounding the 18-year-old with intent to cause grievous bodily harm. The 18-year-old says he was attacked by a group of masked individuals and produced a machete to protect himself. The earlier incident is said by the prosecution to provide background to the relationships between those involved in the February 2026 violence.

The defence counsel for the 17-year-old, who accepts that he inflicted the fatal wound but denies murder, told the court: "He did not know the 18-year-old or Mason. He had never communicated with either of them. He was not aware of previous fights between the 16-year-old, Mason, the 18-year-old or any other person.

"On February 18, he had a machete with him, which he carried for his own protection. He was concerned about the community in which he lived and the wider teenage community in Northampton.

"He did not expect or know there would be any violence that day.

"Once at the skate park, he was aware of two men. He did not know who they were or whether they posed a threat. When they were closer, he saw them armed with machetes and was scared for his life.

"He lunged at the 18-year-old and connected. He looked towards Mason and the 16-year-old. He thought if he did not act, the 16-year-old would be killed.

"Mason stabbed him to the right of his chest. In sheer panic, he stabbed Mason in the chest."

The defence counsel for the 16-year-old told the court : "He took his knife out to protect himself. Mason was swinging his knife at him. Mason did not strike the 16-year-old's body. The 16-year-old did not strike Mason's body. The 17-year-old struck Mason to the ground with his knife.

"The 16-year-old denies causing harm to Mason and the 18-year-old. His actions on February 18 were lawful as he was acting in self-defence."

The defence counsel for the 18-year-old told the court: "He was not a principal in the death of Mason and was not encouraging it.

"He was a victim of a stabbing by a group of masked individuals. He was stabbed twice, once in the chest, which made him fall to the ground, then once on the thigh when he was on the ground.

"He denies any arrangement or agreement to be stabbed or be stabbed at. There was no arrangement, understanding or plan between them all to engage in violence.

"All of his actions were in self-defence. He took out a machete to scare off the other males. At no stage did he use his knife to make any contact with the other males or intend to do so.

"He did not intend for anyone to die or be caused grievous bodily harm."

The defence also addressed the earlier machete incident on April 6, 2025, involving the 16-year-old and 18-year-old defendants.

His defence counsel said: "He was a victim of a stabbing that day by a group of masked individuals. He perceived a real risk of being stabbed. In those circumstances, he produced a machete as a precautionary and defensive measure to scare the other males."

The judge told the jury that a person was entitled to defend themselves if they were under attack or genuinely believed they were under attack, provided they used reasonable force.

He also explained that someone could be guilty of murder if they intentionally encouraged or assisted another person.

Closing, addressing the jury, Crown Prosecution’s Mark Haywood KC said: “We say that on the evidence you’ve heard, you can be sure that in April 2025 it was the 16-year-old who inflicted those life-threatening injuries on the 18-year-old, and it was the 16-year-old who only narrowly escaped serious injury himself because, in the event, the 18-year-old lost his grip and dropped his own machete, the one he had swung at the 16-year-old [who was 14 at the time] but failed to land a blow.

“And so, in February this year, the 16-year-old and the 18-year-old were once again on opposing sides. Together this time with the 17-year-old and Mason Miller respectively. All four willingly taking part in a consensual machete fight.

“We suggest intending nothing less than really serious harm and all four willing to accept the inevitability they would have to defend themselves against their opponents' identical intentions against them. It is only in this sense the avoiding and parrying of blows while seeking advantage for oneself that the word self-defence has any relevance in this case. Lawful self-defence didn't arise at any stage.”

The court heard that three additional counts had also been added to the indictment.

The judge explained that the new charges were alternatives in law to more serious offences and had to be put to the defendants.

The new counts are:

Count 1a: The 16-year-old is accused of unlawfully and maliciously wounding the 18-year-old on April 6, 2025. He pleaded not guilty.

Count 2a: The 18-year-old is accused of attempting to wound the 16-year-old on April 6, 2025. He pleaded not guilty.

Count 7a: The 16-year-old and 17-year-old are accused of unlawfully and maliciously wounding the 18-year-old on February 18, 2026. Both pleaded not guilty.

The additional charges bring the total number of counts on the indictment to 12.

The original indictment contained nine counts relating to the April 2025 and February 2026 incidents.

These include:

April 6, 2025

Wounding with intent: The 16-year-old is accused of wounding the 18-year-old with intent to cause grievous bodily harm. He denies the charge.

Attempted wounding with intent: The 18-year-old is accused of attempting to wound the 16-year-old with intent to cause grievous bodily harm. He denies the charge.

Possession of an offensive weapon: The 16-year-old is accused of possessing a machete in a public place. He denies the charge.

The 18-year-old also faced a separate offensive weapon charge relating to the April 2025 incident. He pleaded guilty to that charge, which is not before the jury.

February 18, 2026

Murder: All three defendants are accused of murdering Mason Miller. All three deny the charge.

Manslaughter: All three are also accused of unlawfully killing Mason, as an alternative to murder. All three deny the charge.

Attempted murder: The 16-year-old and 17-year-old are accused of attempting to murder the 18-year-old. Both deny the charge.

Wounding with intent: The 16-year-old and 17-year-old are accused of wounding the 18-year-old with intent to cause grievous bodily harm. Both deny the charge.

Possession of an offensive weapon: The 16-year-old and 17-year-old are each accused of possessing a machete in a public place. Both deny the charges.

The 18-year-old also faced a separate offensive weapon charge relating to the February incident. He pleaded guilty to that charge, which is not before the jury.

The trial continues.