The family of an actor who died at an east London party attended by ex-Libertines singer Pete Doherty have threatened private prosecution if the police fail to bring charges.
Sheila Blanco claims her son Mark was unlawfully killed when he fell from a balcony at a flat in Whitechapel in December 2006.
After two Scotland Yard investigations, detectives have been unable to confirm if the 30-year-old committed suicide or fell because of a "criminal act", prompting the Blanco family to conduct their own investigation.
Their findings, which are claimed to prove that the Cambridge graduate was unlawfully killed, have been studied by the Crown Prosecution Service (CPS) and prosecutors are expected to make a decision on whether to bring charges later this week.
Mrs Blanco, who is expected to meet CPS officials at the Old Bailey on Thursday, said: "We will undertake a private prosecution if they (the CPS) come back with negative results - giving up is not an option."
The family's report was handed to the police last July. It includes a study by neurobiology expert Professor Richard Wassersug that found Mr Blanco could not have deliberately jumped and sustained the head injuries he did.
"The two explanations we have are that Mark was either pushed over the railings or that he was not conscious and dropped over the railings. This has come from legal minds and as a lay person it defies all common sense if they decide not to prosecute."
Mr Blanco had attended a party at a flat owned by Paul Roundhill in Whitechapel in December 2006 to invite Doherty to a performance of a play he was starring in. He left after a confrontation with the singer, Mr Roundhill and the star's minder Johnny Jeannevol. Shortly afterwards he was found on the ground outside having fallen from a first-floor balcony. He was taken to hospital with severe head injuries and died the following day.
Scotland Yard's initial probe found Mr Blanco jumped deliberately, but a coroner ordered a second independent investigation after recording an open verdict at the inquest. Officers then found that either Mr Blanco committed suicide or he fell because of a "criminal act", but could not say which. This prompted the Blanco family to pay for their own specialist reports on the death.
Mr Roundhill, Doherty and Mr Jeannevol deny any wrongdoing.