The prosecution in the Billie-Jo Jenkins murder retrial was "desperate to find a motive", it has been alleged.
Sion Jenkins denied claims that Billie-Jo had flirted with him
It hinted at a false sexual motive because there was "no reason" for Sion Jenkins to kill his 13-year-old foster daughter, the Old Bailey heard.
Summing up, Christopher Sallon QC, defending, said Mr Jenkins was the victim of a miscarriage of justice.
Sion Jenkins, 48, now of Lymington, Hampshire denies murdering Billie-Jo at home in Hastings, East Sussex in 1997.
'Frenzied and psychopathic'
Billie-Jo was battered to death with an iron tent peg as she painted the patio doors.
Mr Sallon questioned why the prosecution had included references to Billie-Jo flirting.
He said it had failed to find a motive that would have led Mr Jenkins to launch a "frenzied and psychopathic" attack on the girl.
Mr Sallon insisted there was also no evidence that Billie-Jo had been sexually abused by her foster father.
He said Jenkins' former wife Lois had been a nurse and had an MA in social work and training in child protection.
"If anything had been going on, would someone not have heard of it?" said Mr Sallon.
"It is rare that there is an absence of motive."
He described that absence as "a fundamental weakness in the case".
He also insisted that Mr Jenkins would not have been able to kill Billie-Jo, clean his hands and return to acting normally with his other daughters within the three to five minutes alleged by the prosecution.
The case continues.