An "internet predator" has admitted stabbing to death a 14-year-old boy after meeting him online.
Breck Bednar, of Caterham, Surrey, was found with a neck wound at a flat in Grays, Essex, in February.
Lewis Daynes, 19, of Rosebery Road, Grays, was due to stand trial at Chelmsford Crown Court on a charge of murder but admitted the offence.
It is believed Daynes met Breck, a student at St Bede's School in Redhill, while playing video games online.
Barrister Richard Whittam QC said it was the prosecution's case the murder "involved a sexual, sadistic motivation".
In a statement following Daynes' plea, Assistant Chief Constable Gavin Stephens, said Surrey Police's handling of the case had been referred to the Independent Police Complaints Commission (IPCC).
"In December 2013 a call was made to Surrey Police by a relative of Breck expressing concerns around online grooming," he said.
"Following Breck's death we carried out a review of practices in our call handling centre and implemented changes to improve the way information is handled and shared.
"Due to the prior contact the case was referred to the IPCC. They have since decided to conduct an independent investigation into the actions taken by Surrey Police following this communication."
At the time of the killing, Breck's mother Lorin LaFave, said her son was "brutally murdered" by an "internet predator" and posted a message to his favourite band Coldplay on Facebook asking them to raise awareness of the dangers teenagers face online.
Speaking after the hearing, Ms LaFave said she was left "heartbroken" by her son's death.
"He was murdered on my birthday this year and so much of me died as well," she told reporters outside court.
She described Breck as an "amazing, clever, beautiful boy", saying that he had "so much to give to this world".
The teenager was a member of the Air Training Corps and attended St John the Evangelist church in Caterham, his family said.
They have set up a memorial foundation in his name to raise awareness of the dangers online.
"I want Breck's tragedy to open the eyes of everyone to recognise the dangers of online predators. It is a very real danger today. We all need to look after each other," said Ms LaFave.
Mrs Justice Cox adjourned sentencing to 12 January.