Teenager found guilty of murdering boy, 17, in knife attack at party

Charlie Cosser was stabbed three times in the chest at the outdoor event called BalFest.

Charlie Cosser died after being stabbed at a party in Warnham, West Sussex, in July 2023 (Sussex Police/PA) (PA Media)

A teenager who stabbed a 17-year-old boy to death on a crowded dancefloor at a party has been found guilty of his murder.

Charlie Cosser was stabbed three times in the chest at the outdoor event called BalFest, attended by around 100 people, at a farmhouse in Warnham, West Sussex, on July 23 last year.

The teenage defendant, who was 16 at the time and is now 17, will face life imprisonment for the attack following a trial at Brighton Crown Court.

He was found guilty of Charlie’s murder and guilty of having a bladed article in unanimous verdicts on Tuesday.

Members of Charlie’s family, who attended court every day, cried and hugged each other as the verdicts were given.

In the darkness and noise of a crowded dancefloor his use of the knife and blows of the knife went unnoticed by those in the vicinity

Prosecutor Alan Gardner KC

The trial heard that a fight broke out between the defendant, Charlie and two other boys on the dancefloor after the defendant and his friends were asked to leave the party.

A partygoer captured part of the violence on video as she began filming her friends dancing to the song Toxic by Britney Spears under disco lights in the marquee.

Opening the case on May 13, prosecutor Alan Gardner KC said: “In the darkness and noise of a crowded dancefloor his use of the knife and blows of the knife went unnoticed by those in the vicinity.

“The defendant stabbed Charlie Cosser with that knife as they came together on the dancefloor.”

Jurors heard from numerous witnesses who attended the party that night.

A friend of the defendant said the teenager had drunk an “excessive amount” of vodka and appeared “angry” after an older man had unsuccessfully tried to make him leave the party because of his apparent behaviour towards a young woman.

The witness described hearing “arguing” and “shouting” inside the marquee before the defendant and others started fighting.

Later on, the young man found the defendant next to the road with his hands and trousers “covered in blood”.

“The top of his joggers down to his knees were almost like drenched,” he told the court.

He and another friend of the defendant also said they heard the teenager say “I’ve stabbed someone”.

He didn’t have a T-shirt on and he had blood all over his chest

Witness Harriet West

Other party guests, including Harriet West, described seeing a boy, believed to be Charlie, lying on the ground as she approached a man in hi-vis who was acting as security.

She said: “He didn’t have a T-shirt on and he had blood all over his chest.

“I just left. The man in the hi-vis was going on to his knees.”

The court heard that Charlie was still conscious when police arrived at 12.30am and was able to tell them his name, address and date of birth.

He suffered a cardiac arrest on the way to hospital, with internal bleeding caused by a cut to his aorta, the main artery from the heart.

The teenager, from Milford, Surrey, also known as “Cheeks”, died two days later, on July 25.

Following the defendant’s arrest, jurors heard that bloodstains on his trainers were tested and found to be his own blood.

The court was also told the defendant accepted that he burned the clothes he was wearing at the party in a firepit in the garden, because he said they were covered in his own blood.

The teenager had suffered an injury to his left hand, which the prosecution alleged happened when he was using the knife to stab Charlie.

The knife has never been found.

The youth chose not to give evidence in the trial but denied murdering Charlie and having a bladed article.

He originally pleaded guilty to murder during his first appearance at Lewes Crown Court on July 28 last year, but before being sentenced he successfully applied to withdraw his guilty plea, prompting the trial to take place.

Charlie’s family previously paid tribute to their most caring, cheeky and loving son and brother who had a “ridiculously silly sense of humour”.

Since his death, they have set up a charity called Charlie’s Promise, dedicated to fighting knife crime across Surrey and the UK.

The defendant will be sentenced on June 19.