He claims police pressured and "coached" him into falsely confessing he was present when the 27-year-old was raped, bashed, and stabbed on December 18, 2008 at a Galbraith Ave gang pad over an alleged debt.
The Crown says Fawcett - then aged 21 and known within gang circles as "Muck Dog" - either took part in the killing or was there as a party to Ms Manning's brutal murder.
Her partly naked body was discovered floating in the Avon River by a kayaker the day after she was killed.
In his summing-up, Justice Gendall told the jury: "You are the sole judges of the facts."
He said they must set aside any feelings of sympathy and prejudice and ensure their decision is not swayed by emotion. The onus of proof, whether the charge was proved beyond reasonable doubt, lay with the Crown, he said.
Commenting on Fawcett's unusual decision to represent himself on such a serious charge, Justice Gendall said that, like any defendant, he had an "absolute right" to do so.
"You are not to read anything in that decision or to think anything ill of that."
Justice Gendall also directed the jury on the alternative possible verdict of manslaughter.
The Crown accepts that Fawcett was not necessarily the main killer, but was at least party to the murder, and therefore guilty of murder.
The Crown says it is a clear case of murder, and not manslaughter.
But the judge said if the jurors found Fawcett not guilty of murder as a party, then they should go on to consider whether he was guilty of manslaughter as a party.