A young woman was stabbed by a 16-year-old boy after inhaling laughing gas on Christmas Eve, a court heard.
Kacey Clarke, 22, was knifed at a flat in Bermondsey on December 24 last year.
Police officers attended along with paramedics who provided emergency first aid but Ms Clarke died at the scene.
The 16-year-old, who cannot be named for legal reasons, was arrested a short time later.
The court was told Ms Clarke had been taking ‘balloons’, slang for inhaling nitrous oxide, before she was attacked and clumps of the defendant’s hair were found on the floor of the flat.
Jane Osborne, KC, prosecuting, told jurors: “Unfortunately, Kacey Clarke was never to see Christmas day, because on Christmas Eve, she was stabbed by this defendant and died.”
The court heard that a relative had suspected Ms Clarke been taking ‘intoxicating substances’ earlier that day as she had been in contact with her by phone.
The phone messages showed she had been taking ‘balloons’, the court was told. Ms Osborne said the relative had challenged Ms Clarke about taking laughing gas and said she “shouldn’t be boring because it was Christmas.”
Police and paramedics were later called to an ‘incident’ at the flat at 22:02pm.
The first medic to enter the flat found Ms Clarke lying on the kitchen floor and unresponsive.
“There was a single stab wound that was to the right-hand side of her chest wall, around the 4th/5th rib which was 3-4cm long,” said the prosecutor.
“At the time that the paramedics arrived Kacey Clarke was in cardiac arrest.
“In order to facilitate the necessary medical treatment, a space was cleared in the living room, so that Kacey could be moved from the kitchen, where she was lying when the paramedics arrived, into the lounge.
“Whilst she was there the medical team did everything they could to try and save Kacey Clarke.
“They performed surgery on her in the living room to ensure that the heart was undamaged and capable of functioning – they found no damage to the heart but there was substantial bleeding to the right lung which was significantly damaged.
“Despite inserting breathing tubes to ensure that oxygen was entering the body and carrying out blood transfusions to replace the blood that was being lost, Kacey never regained consciousness. Her life was pronounced extinct at 22:42.”
The court was told the teenager was arrested and made no reply to caution.
“The arresting officer noticed that he had a scratch to his neck and also an injury to his left arm,” said Ms Osborne.
He also had a rip to the rear of his T-shirt, the court was told.
It was said that when arrested for murder the 16-year-old ‘broke down’ and said ‘For What? You’re lying, you’re lying….”.
Police later found a ‘large collection’ of nitrous oxide cannisters in his bedroom along with a sheaf to a knife on the floor, but with no blade, the court heard.
Photographs were then taken of the defendant’s injuries and a blood stain on the defendant’s right foot between his big toe and the next one.
“The blood, when later analysed, was found to match that of Kacey Clarke,” said Ms Osborne.
The 16-year-old was examined and found with “a 2cm x 3 cm red bruise with no skin loss, no bleeding and minimal hair loss, 2 cm above the hair line.
“The second injury noted was a red blistered wound on his inner left arm, which he told the nurse he had sustained a few days previously from a nitrous oxide cannister,” said Ms Osborne.
“The third injury was a scratch to the left hand side back of his neck, which was about 2cm long with a faint cluster of smaller linear lines to the right.
“Once at the police station and having recovered from the initial shock, the defendant remained entirely calm, and at times was laughing and joking with officers saying that the charges would go nowhere. He didn’t ask about Kacey Clarke at any point,” said Ms Osborne.
“When the flat was searched clumps of his hair were found which appeared to have been ripped from his head.
“There were clumps of hair that were seized from near the door of the kitchen. Those clumps of hair, when later analysed, had the appearance of having been ripped from the scalp and they were found to belong to the defendant,” she added.
Police later analysed footage from a CCTV camera belonging to the occupants of a neighbouring flat.
The prosecutor told jurors: “A clip which shows no people on the footage but contains audio which consists of a male saying ‘I’m gonna ching you up yeah’ and a female voice saying ‘Just f–king stop’ and the male finally saying ‘I’m going to kill you’.
“This clip lasted only 11 seconds, and was recorded shortly before 22:00.”
The 16-year-old, of south London, denies murder and an alternative charge of manslaughter.