A schoolboy who stabbed his former girlfriend to death after she finished with him has been jailed for life with a minimum term of 12 years and six months.
Thomas Griffiths, now 18, stabbed Ellie Gould at her home in Calne in Wiltshire on May 3 after she ended their relationship.
He left the 17-year-old lying in a pool of blood on the kitchen floor, where her father discovered her four hours later.
Bristol Crown Court heard on Friday that Griffiths had placed Ellie’s hand on the knife in her neck to make it look as though she had killed herself.
On the day of the murder Griffiths returned to school after murdering Gould and was provided with "pastoral care" by unsuspecting staff, police said.
Both Griffiths and Ellie, 17, were pupils at Hardenhuish School in Chippenham, Wiltshire, and started a relationship in January.
Ellie, an academic and committed student, decided to end the relationship on May 2 to concentrate on hobbies including horse riding and her studies.
The following day, learner driver Griffiths was taken to school by his mother but he secretly returned to his family home in Derry Hill by bus.
He illegally drove his Ford Fiesta alone to Ellie's family home in Springfield Drive in Calne, where he was let inside at about 10.30am.
Griffiths has since claimed that the pair were studying together but began to argue.
Detective Chief Inspector Jim Taylor, of Wiltshire Police, said Griffiths is the only person who knows what happened inside the property.
"He remembers placing his hands on her neck. He then says he can't remember what happened," Mr Taylor said.
"The next bit he does remember is coming around having stabbed Eleanor."
Griffiths attempted to clean up the house and is believed to have washed his shoes there before driving home in his car.
The teenager deposited a bag of bloodstained items a short walk away from his house and was spotted by a neighbour on his return.
"He was very upset and distressed and was presenting with some scratch marks to his neck," Mr Taylor said.
"They asked him about those scratch marks. He said he was self-harming through stress, the stress of exams and also ill relatives.
"The neighbour, not knowing the circumstances of him being there, offered to take him back to school, which they did.
"The school provided him with pastoral care and telephoned his mum to come and pick him up, which she did."
Griffiths, who had placed clothes in the washing machine at his home, asked his mother to drive him to a friend's house in Chippenham.
At 3pm, Ellie's father Matthew Gould returned home and found his daughter dead in the kitchen.
She had suffered a minimum of 13 stab wounds to her neck, leaving what Mr Taylor described as a "scene of total devastation".
Mr Gould called emergency services, with police and paramedics arriving a short time later.
A murder investigation was launched and officers were sent to speak to Griffiths within a few hours.
He was arrested on suspicion of murdering Ellie and was brought to Melksham Police Station for questioning.
In police interviews, Griffiths insisted that he had remained at his family home all day.
Mr Taylor said the defendant's account began to "fall to pieces" after police pieced together CCTV footage of his car driving towards Ellie's home and the location services on his iPhone.
The WiFi router at his home also documented when he arrived and left.
Griffiths was charged with murder following that evidence, along with forensic tests showing Ellie's blood was on his shoes.
Mr Taylor said: "Over the coming weeks, a raft of evidence was presented to his defence team which clearly showed that he was lying in his account."
Griffiths pleaded guilty to murder at a pre-trial preparation hearing at Bristol Crown Court on August 29.
He was aged 17 at the time but Judge Peter Blair QC lifted reporting restrictions, meaning that he could be publicly identified.
Mr Taylor said: "Thomas Griffiths presented as a normal 17-year-old boy with the world at his feet.
"He was a fairly good student, no evidence of misconduct, no previous convictions and nothing in his behaviour from what we have found in our investigations that would give any indication that anything like this was going to happen."
He said Griffiths still "refuses to account for his actions" and has never revealed why he murdered Ellie.