The boy, now 17, had admitted manslaughter but denied murdering 15-year-old Holly in Hexham, Northumberland, in January 2023.
After a five-week trial at Newcastle crown court the boy, who was 16 at the time and cannot be identified, was found guilty of murder.
Holly, from Haltwhistle, was murdered after she had finished her day at school in Hexham and was walking round shops with friends. David Brooke KC, prosecuting, said the defendant was following Holly and her friends from a distance.
"It is quite clear he was being careful not to be seen by them for the next 45 minutes or so," Brooke said.
The boy made himself known to Holly, who was not happy to see him, the court heard. She agreed to speak to him down an alleyway.
"What Holly didn't know was that (the defendant) had brought a knife with him," Brooke said.
In less than a minute, the defendant inflicted 36 knife wounds on Holly, stabbing her 12 times and slashing her 19 times. She suffered a further five defensive injuries to her hands. A 16-year-old boy who was with Holly tried to help and was also stabbed.
Denne historien er fra August 30, 2024-utgaven av The Guardian.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
Allerede abonnent ? Logg på
Denne historien er fra August 30, 2024-utgaven av The Guardian.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
Allerede abonnent? Logg på
Consumer champions
BT has left my father, 80, with no phone for months.
Money hacks How to save a bundle on children's clothes
Charity shops can be a goldmine for bargains - use the Charity Retail Association's online search page to find ones that stock children's clothes, or in London, head to one of FARA's 14 stores that specialise in kids' clothes.
University students Why are tuition fees going up and who does it affect?
The government has announced fees in England will rise to £9,535 in 2025. Shane Hickey gives you the lowdown on the changes
British Airways owner IAG's profits up 15%
Strong demand for transatlantic travel has bolstered the profits of International Airlines Group, the owner of British Airways, with the UK national carrier outperforming rivals despite widespread European flight delays.
Taking the plunge Seven date ideas that won't break the bank
You certainly don't need to spend a fortune to have a fun and romantic time, whether it's your first date or the 101st.
The price of love How much does dating cost - and who pays the bill?
Hinge+ costs £14.99 for a week, £24.99 for one month, £49.99 for three months and £74.99 for six months. One week of HingeX costs £24.99, a month is £44.99, three months £89.99 and six months comes in at £129.99.
China offers £646bn to local government but balks at big stimulus
China has announced 10tn yuan in debt support for local governments and other economic measures, but stopped short of a \"bazooka\" stimulus package many analysts expected.
Secret diary of TV freelancer Brutal hours, fear, panic - and finally a kick in the teeth
An anonymous producer writes about their experiences of the brutal hours, low budgets and high stress of television production
Shares plunge for housebuilder Vistry after new profit warning
Shares in the FTSE 100 housebuilder Vistry have plunged after it issued a second profit warning in as many months and said cost overruns on building projects were worse than previously thought.
Families may get post office compensation, says minister
The postal minister has said that family members and employees of post office branch owners who have not been eligible to make claims over the Horizon IT scandal may be allowed to apply for compensation.