British banker Rurik Jutting is charged with torturing and murdering two Indonesian women he paid for sex, in one of the most gruesome cases the city has seen.
Mr Jutting, 31, has pleaded guilty to manslaughter by reason of diminished responsibility.
He has denied two counts of murder.
"You must approach this with intellectual honesty, not coloured by passion or disgust that you feel at the dreadful acts which the defendant has admitted he carried out," Deputy High Court Judge Michael Stuart-Moore told the jury.
"The point that he has an appalling private life is neither here nor there."
Police found the bodies of Sumarti Ningsih, 23, and Seneng Mujiasih, 26, in the banker's luxury flat in November 2014.
Prosecutors say Ms Ningsih was tortured for three days after arriving at the flat in Hong Kong's Wan Chai district on 25 October.
In one video shown to the jury on Tuesday, he is heard asking her if she loved him before torturing her.
The footage was shown to jurors on individual screens.
Judge Stuart-Moore told the jury of four women and five men to consider if Mr Jutting was of "abnormal mind" at the time of the killings.
The former Bank of America employee has been diagnosed with narcissistic personality disorder and sexual sadism.
Defence witness Richard Latham, a consulting forensic psychiatrist in the UK's National Health Service, said Mr Jutting's disorders had progressed to the "most severe end of the spectrum" by the time of the killings.
He also added that Mr Jutting's ability to control his behaviour was "substantially impaired".
However, the prosecution argued that Rurik Jutting was able to form judgements and exercise self control, filming his victim's torture and shooting videos where he discussed various issues such as the killings and his sexual fantasies.
The accused could face a mandatory life sentence if he is found guilty of murder.
Jurors are due to begin considering their verdict on Tuesday.
A judge has told jurors in a high-profile Hong Kong murder trial to reach a verdict "intellectually" and put aside their emotions and disgust.