Rurik Jutting, a British banker accused of the 2014 killings of two Indonesian women, has entered a plea of not guilty to two murder charges in Hong Kong.
The judge has told prospective jurors that the trial is expected to be "particularly horrifying", with photographic evidence of one victim's torture.
The Cambridge graduate is charged with the murders of Sumarti Ningsih and Seneng Mujiasih, whose bodies were found in his upmarket apartment near Hong Kong's Wan Chai red-light district.
The case is expected to highlight the Asian financial hub's inequality and privileged lifestyle of its wealthy expat elite.
Jutting looked visibly slimmer than his court appearances last year. When the clerk asked what his plea was to the two murder charge, he replied: "Not guilty to murder by reason of diminished responsibility, but guilty of manslaughter," which the prosecutors refused to accept, meaning the trial on the murder charges will proceed.
A third charge was also read out - unlawful burial of Sumarti Ningsih's body, to which Jutting pleaded guilty.
One of the women's bodies was found stuffed in a suitcase left on a balcony, while the other had knife wounds on the neck and buttock, according to initial police reports.
Judge Michael Stuart-Moore told jurors before the selection began that there were "particularly horrifying aspects to this case, with one victim subject to extreme violence and cruelty amounting to torture" before she died.
He said the evidence includes colour photographs that "are not pleasant photographs to look at. They are extremely upsetting". He added that "the defendant even recorded on his iPhone part of the torture he inflicted on his first victim", which will be shown to the jury.
"Much of what the jury will see or hear is very disturbing indeed," he said, but added that Jutting was entitled to a fair trial.
While Jutting's initial guilty manslaughter plea was rejected, the judge told jurors that they could still decide between finding him guilty of murder or manslaughter.
Jutting worked for Bank of America-Merrill Lynch in structured equity finance and trading. If convicted, he faces life in prison.