Girl X also sent her co-defendant a picture of a handwritten note detailing the plan to kill the teenager, prosecutors told the jury.

The two teenagers, who cannot be named for legal reasons, are on trial at Manchester Crown Court accused of murdering the 16-year-old in Culcheth Linear Park near Warrington in Cheshire on 11 February.

The note girl X sent to boy Y was entitled: "Saturday 11 February 2023. Victim: Brianna Ghey."

Police found the note in the girl's bedroom after she was arrested the following day, alongside others about plans to target further victims.

One read: "Give them alcohol with sleeping pills, slit throat, dismember body, place pieces in bin bags."

Prosecuting, Deanna Heer KC read out the note about Brianna, which read: "Meet boy Y at wooden posts 1pm. Walk down to library ... bus stop.

"Wait until Brianna gets off bus then the 3 of us walk to linear park. Go to the pipe/tunnel area.

"I say code word to boy Y. He stabs her in the back as I stab her in the stomach. Boy Y drags the body into the area. We both cover up the area with logs etc."

Another message saw girl X tell boy Y she was "excited as f*** for 11 February", the court heard.

"It is clearly a plan to kill Brianna Ghey," Ms Heer told the jury.

Girl X and Brianna, who was transgender, exchanged Snapchat messages while the three of them were in the park, Ms Heer said.

At 3.06pm girl X sent Brianna a message, saying: "Girl where are you?" before deleting their chat history.

This is when the murder is believed to have taken place, Ms Heer alleged.

A 999 call was made seven minutes later at 3.13pm and Brianna was pronounced dead at 4.02pm, having suffered multiple stab wounds.

Accused sent victim messages after death as 'false defence'

The following day girl X messaged Brianna's phone saying: "Girl, is everything okay? Some teenage girl got killed in Linear Park its on news everywhere.

"And why did you ditch us for some random man from Manchester. Like wtf. That is so f***** up."

Later girl X's mother would tell police her daughter's version of events, whereby the trio were sitting on a bench in the park when Brianna said she was going to meet "a 17-year-old from Manchester".

Ms Heer said: "The prosecution say that was an obvious attempt by girl X to set up a sort of false defence, were anybody to look at her phone in due course."

According to Ms Heer, girl X later posted a tribute to Brianna on Snapchat, describing her as an "amazing friend" and that it was "so f****** sickening" what had happened.

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'Don't worry police are s**t here'

At around 11pm on the day of the killing, girl X messaged boy Y saying: "Do you have anxiety about getting caught?"

Boy Y responded: "Probably." Girl Y then text him again saying: "You're not going to get caught don't worry. Police are s**t here."

Further conversations between the two read out in court revealed girl X instructing boy Y: "Make sure story adds up."

Boy Y had searched for information on criminal offences around withholding information on the Crown Prosecution Service website.

Ms Heer said: "He was looking up information about measures to support people giving evidence and bail."

The jury heard blood had been found on boy Y's jacket and trainers when his bedroom was searched following his arrest.

Fizzy drinks bottles with the pair's DNA on also placed them at the park.

Both defendants deny murder and blame each other for Brianna's death. The trial continues.