The jury in the trial of pub chef Mark Dixie were asked if they could be sure Sally Anne Bowman was not killed by her boyfriend.
Closing the defence case, Anthony Glass QC told the Old Bailey jury unless they were certain Sally Anne's boyfriend Lewis Sproston could be 'excluded', the only verdict they could return was not guilty.
Dixie, 37, denies murdering Sally Anne, 18, on September 25, 2005, but admits having sex with her corpse.
In his closing argument Mr Glass said: "If the situation was that you couldn't be sure that Lewis Sproston is excluded then the verdict is not guilty, however much you may detest the quality of Mark Dixie's defence."
He added: "There is plenty of evidence to prove that Mark Dixie had sexual intercourse with Sally Anne Bowman, there is nothing to prove that he was the killer.
"You may be thoroughly disgusted with what my client has told you.
"You can't be sure about the exclusion of Sproston."
Earlier the court heard the prosecution's closing argument.
Prosecutor Brian Altman told the court: "He (Dixie) has put up a smokescreen before you in the hope that you will be gullible and fall for his story but it is not just incredible but pure fantasy."
The jury are due back in court tomorrow when the judge is expected to sum up the case.
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