Two teenagers in Britain will be sentenced on Friday for murdering a 16-year-old transgender girl in a "frenzied and ferocious" knife attack.

The pair, who will be named publicly for the first time after the judge in the case agreed to lift an anonymity order, killed Brianna Ghey in Warrington, northwest England, in February last year.

Their victim was stabbed 28 times in the head, neck, back and chest. Her body was discovered by dog walkers in a park.

The case drew international attention and shock in Britain, in particular given the perpetrators were aged 15 at the time of the murder.

Under-18s on trial in the UK are typically granted anonymity, although the media can challenge that restriction in the event of a conviction in the most serious cases.

A jury of seven men and five women convicted the two, now aged 16, after nearly five hours of deliberations, following a four-week trial at Manchester Crown Court.

Addressing the pair before they were returned to prison ahead of sentencing, judge Amanda Yip told them she had to impose life terms for their convictions.

"What I have to decide is the minimum amount of time that you will be required to serve before you might be considered for release," the judge said, adding she would consider reports on both before deciding.

'Beyond belief'

During the trial, the court heard how the defendants had discussed killing Brianna in the days and weeks before she died.

Jurors learned one of the accused, referred to as girl X, had downloaded an internet browser app that allowed her to watch videos of the torture and murder of real people, in "red rooms" on the "dark web".

She had developed an interest in serial killers, making notes on their methods, and admitted enjoying "dark fantasies" about killing and torture, the court was told.

The pair later drew up a "kill list" of four other youths they intended to harm, until Brianna had the "misfortune" to be befriended by girl X, who became "obsessed" with her, according to prosecutors.

Ghey had thousands of followers on the social media platform TikTok, but in person was a withdrawn, shy and anxious teenager who struggled with depression and rarely left her home, the jury heard.

Deputy chief crown prosecutor Ursula Doyle said after the verdict that the case had been "one of the most distressing" that she had ever dealt with. 

"The planning, the violence and the age of the killers is beyond belief," she noted.