The youth was heard 'mumbling' he had been stitched up after police charged him with the murder and rape of Viktorija Sokolova at Wolverhampton's West Park.
It comes after he revealed to police he started to get 'annoyed' with the 14-year-old schoolgirl, who would visit his home at night.
Ms Louise Oakley, junior prosecuting counsel, said: "He asked if the police had matched the DNA because he had not done it and said he was her friend, and also said that he had been framed."
The youth, who cannot be named because of his age, denies murder, rape and having sex with her dead body.
He made no comment when police charged him but soon after was heard claiming he had been set up while at the custody desk, Ms Oakley told jurors on Friday.
'Heard about it on the news'
A prepared statement handed to interviewing officers claimed the defendant 'knew nothing about the murder' and 'only heard about it on the news'.
The youth claimed Viktorija would initiate conversations online but he decided to break off communication when she started appearing at his home during late-night visits, Wolverhampton Crown Court heard.
During the trial, jurors were told Viktorija was bludgeoned to death after receiving more than 20 blows in the park’s wooden pavilion - known as the ‘black house’.
A pair of hoop earrings belonging to the teenager were discovered after her body was found slumped over a park bench.
Two of her teeth and a further tooth fragment were seen lying on the floor, the court was told.
Full coverage from the trial:
Ms Oakley said a bloodstained Nike baseball cap appeared pink but the piece of headwear was actually white and had been heavily blood stained.
She added: "The expert concludes that these teeth had been knocked out of Viktorija Sokolova's mouth by a violent, heavy blow, or contact with a hard object or surface.
"Six other front teeth were found to be chipped, which could have also resulted from a heavy blow causing opposing teeth to come together."
The defendant has admitted having sex with the teenager on the night she died in West Park, where the Facebook friends had arranged to meet late at night on April 11.
He maintains Viktorija consented and was alive and well when he left her in the park.
The trial continues.