Chevonea Kendall-Bryan plunged from her bedroom window on the top floor of Seldon House in Battersea, south-west London, in March last year.
An inquest heard how the schoolgirl had been forced into performing sex acts on two boys at a party just a month earlier and was begging a teenage boy to delete the mobile phone footage of the incident when she fell.
Coroner Bernard Richmond QC said he believes Chevonea was leaning out of the window to convince one of the boys, known as E6, she would jump if he did not erase the mobile phone footage.
But he believes she never intended to follow her threat through.
‘It is clear that Chevonea was of the view that there was a video, and that video was under the control of, or certainly could be influenced by E6’, he told Westminster Coroners Court.
‘We have the text where she is begging him to delete the video.
‘I suspect strongly what happened is Chevonea was saying to him something along the lines of it will finish her off if the video gets out.
‘His approach was to be unsympathetic, or to be, as he thought, funny, or maybe being unkind – who knows?
‘In any event, he was not giving her reassurance she needed, and she was trying very hard to demonstrate how serious the fact was that this will “kill her”.
‘The most likely explanation is she was trying to persuade him she would do something to herself.
‘She probably thought she could lean out of the window, and she toppled over.
‘This was a ghastly, ghastly accident.’
Following five days of evidence, Mr Richmond concluded he does not think Chevonea leapt to her death deliberately.
‘I am certainly not going to find it was suicide’, he said.
‘I don’t believe, however difficult things were, that Chevonea would deliberately have taken her own life.
‘If she was going to kill herself, I honestly don’t think she would have chosen a way which caused her family so much distress.
‘I don’t even begin to get close.’
Chevonea was bullied mercilessly by fellow pupils at St Cecilia’s School in Wandsworth, south London, for nearly three years before her death.
She cut herself at least three times in school and is said to have tried to swallow a handful of paracetamol tablets during class.
Mr Richmond has identified a catalogue of failures by the school in not helping Chevonea, and even when she was referred to Wandsworth Council social services, her plight was largely ignored.
Just a month before her death, on March 29, 2011, Chevonea told teachers she had been forced to perform oral sex on two boys.
She said a boy known as TG had raped her after a party, and the following day E6 threatened to throw a brick through her window if she did not repeat the act on him.
TG is thought to have filmed Chevonea performing the sex act on E6, though the schoolgirl only learnt of the footage just hours before her death.
Both boys gave evidence to the inquest, denying all knowledge of the sex tape and claiming neither had sexual or physical contact with Chevonea.
But Mr Richmond branded them liars, and said E6, who was outside Chevonea’s home when she fell, knew full well what had happened that day but had not told the inquest.
‘They deliberately lied about what they know’, he said. ‘I will find as a matter of fact that TG and E6 lied.
‘I am quite satisfied that E6 saw Chevonea fall, quite satisfied that TG knows E6, that the video of sex activity involved Chevonea, and that TG filmed it.’
Chevonea’s neighbour Richard Umunegbu said he heard E6 cry ‘this was not meant to happen’ moments after the teenager fell.
Despite concluding that E6 had withheld the truth, Mr Richmond said he does not think the boy, now 16, had egged on Chevonea to jump from the window.
‘I don’t think for a second there is anything about E6 that he would counsel someone to kill themselves’, he said.
‘His silences were profound, he knew plenty of what was going on but also he was profoundly affected by what happened.’
Adjourning the hearing, the coroner praised Chevonea’s family for sitting stoically through five days of evidence.
‘I thank Chevonea’s family for their consistent support of this inquiry, and for conducting themselves with such dignity’, he said.
The inquest will reconvene on Wednesday, January 16, at 9am, for Mr Richmond to sum up the evidence before presenting his official verdict.
He is expected the record a narrative verdict which rules out suicide and suggests Chevonea, of Battersea Park, south London, fell to her death accidentally.