The family of a teenager murdered at a party have said they have been served a “life sentence” as their son’s killer was jailed for life.

Charlie Cosser, 17, was stabbed three times in the chest in a marquee in the grounds of a farmhouse at a private party attended by more than 100 people in Warnham, West Sussex, on July 23 2023.

His killer, Yura Varybrus, who was 16 at the time, was found guilty of murder and having a bladed article following a trial at Brighton Crown Court.

Charlie’s dad, Martin Cosser, said the 17-year-old defendant’s minimum term of 16 years, minus 328 days already spent in custody, was “not enough”.

“It’s not even a year for every year that Charlie lived to at 17. So I can’t say that I’m not disappointed with that. I expected it to be longer than that,” the father-of-three said after the sentencing.

Speaking outside court, he said: “We haven’t even started grieving Charlie yet. We now have to try and start that process of making an adjustment and put behind us what as I say, I have to be honest, it’s been a really disappointing day for us.

“He’s going to spend some time in prison but he will still have a chance to sit in front of a parole board in 15 years and two weeks’ time, and he will be able to sit there and say why he thinks he’s OK to come back out of prison.

“The life sentence is ours. That’s the life sentence … when it’s so severe when life is taken, it’s final. So Charlie is not coming home to us.”

The courtroom on Wednesday was packed with family members as Varybrus was sentenced, and Charlie’s family gave emotional statements to court on the impact Charlie’s death has had on them.

The court heard that more than 700 people attended the funeral of Charlie, also known as Cheeks, who was described by his mother Tara Cosser as “calm” and “chilled”. She said he had never been in a fight and “got along with everybody”.

We have the life sentence, and Charlie has no life

Mrs Cosser told the court about how the 17-year-old had begun an apprenticeship as a groundsman at a private school and was “loving his new adventure”.

He was also “so excited” about the prospect of going on his first holiday with friends to Zante, which he had been saving up for.

She added: “We have the life sentence, and Charlie has no life.

“No sentence will be long enough for my child’s murderer. It doesn’t bring Charlie back.”

The mother-of-three said that before Charlie’s death she was “happy” and had a “normal, happy, family life” but no longer knows what happiness feels like.

Of Charlie, she added: “(The) impact of losing him will last forever. Just numbness and sadness.

“When I do laugh or smile, I feel so guilty.

“I send him a WhatsApp message every morning.”

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

Mr Cosser also told the court how the charity was set up in his memory as a promise he made to Charlie before his life support was switched off.

He said the charity has already raised £135,000.

“How Charlie was killed haunts me and my beautiful family every minute of every day and will haunt us forever,” he said.

“He certainly didn’t want to die, he had his whole life, so many plans, in front of him.”

The grandfather said that if it was not for his other two children “I would end my life”.

“I must force myself to carry on when all I want to do is die,” he said.

I just want to be a normal teenager. I’ve never felt so alone

The family also spoke of how the trial has scarred them forever, and they have seen and heard “unimaginable things”.

Mr Cosser said he has been diagnosed with PTSD which has been made worse from hearing details of the attack on his son, who “hated any confrontation” and “even raised voices”.

Charlie’s older brother Adam Cosser added: “I’m so broken like everyone else in the family that words can’t describe it.

“I’d understand this more if Charlie was in a gang or had a nasty streak. He wasn’t in a gang and he didn’t have a nasty bone in his body.”

His sister Eloise, 16, told the court that Charlie was her “partner in crime since day one”, adding: “He was the person who would make me snort with laughter uncontrollably.

“He was so many more things. He really was my first best friend.”

She described the night police came knocking on the door to tell the family Charlie was in hospital, and that her brother was “so gentle and undeserving of this”.

Seeing him in the hospital, she said she wanted to “switch places” with him so he would not suffer.

If somebody that night, who had heard there was ‘a knife’, ‘a shank’, at that party and reported it, Charlie might well have been alive

Of the defendant, she added: “My brother was fighting for his life while he was eating a Toby Carvery meal.”

The teenager also described how it has affected her ability to sit her GCSEs, instead spending weeks sitting in her brother’s murder trial where she wore his favourite jumper every day.

“I feel like I’m at the darkest point in my life,” she said.

“I just want to be a normal teenager. I’ve never felt so alone.”

Speaking to the PA news agency after sentencing, Mr Cosser said that there were missed opportunities on the night Charlie was killed, adding: “If somebody that night, who had heard there was ‘a knife’, ‘a shank’, at that party and reported it, Charlie might well have been alive.

“There were opportunities missed at that party by a number of people that could have prevented this.

“So if you are that member of the public that I’m talking about … if you notice someone who carries, report them, just report them because you could save a life and a family like ours going through this absolute hell.”