"You've seen some photos of Ms Chen's remains, which you may well have found distressing. You have seen a photo of her smiling and full of life. The death of a person in her prime is always a tragedy regardless of the cause," she said.
"You're acting as judges. Judges have to put personal feelings to one side and so must you."
The Crown's case relied on circumstantial evidence, meaning the jury had to make a series of inferences to reach a guilty verdict.
Justice Katz said reaching the point of "beyond reasonable doubt" was a very high standard and it was not enough that they believed he was probably guilty.
Crown prosecutor Brian Dickey said Ms Chen was likely killed during an hour-long window on the evening of her disappearance.
Phone records showed there was a phone call from the couple's Torbay address to Ms Chen's brother Peter in China at 7.15pm that night.
The Crown suggested that was made by the victim but told the jury she was probably dead before 8.19pm when her friend called and was told by Liu that Ms Chen was out for a walk.
"The defence position is they got the wrong man," Justice Katz said.
Defence lawyer Michael Kan told the jury the Crown had not established where, when, how and why Ms Chen had died, to the required standard.
The motive for the alleged murder, submitted by prosecutors, was the breakdown of the couple's relationship and the fact the victim was planning to cut Liu out of her will.
Mr Kan said friends of the pair believed they were a loving couple and his client had no problem with his partner making a will to divert assets to her family.
The first and likely most important question for the jury was posed by the judge in her question trail.
"Can you be sure Mr Liu killed Ms Chen by an unlawful act, namely an assault?"
Before the jury retired to deliberate, Justice Katz told them there was "no easy formula" for reaching its verdict.
"It's been a long trial and you have a large amount of evidence to consider," she said.
