Robert Xie loses appeal against convictions over 'brutal' Lin family murders

Robert Xie's appeal against his five murder convictions has been dismissed in the NSW Court of Appeal.(AAP: Paul Miller)

Former doctor Robert Xie has lost an appeal against his convictions for violently murdering five members of his family in their Sydney home.

After four trials, a jury found Xie guilty of bashing his newsagent brother-in-law Norman Lin, Mr Lin's wife Lily, their sons Henry, 12, and Terry 9, and Lily's sister Irene, to death while they slept in their beds at North Epping in 2009.

Xie, a former ear-nose-and-throat surgeon who moved to Australia from China, was given five life sentences without parole.

The sentencing judge said he bashed the family to death with a "hammer-like object" strapped to his wrist and that the "brutal" murders were in the worst category of offending.

At Xie's trial, the court heard the two young boys tried to run away from him, and that the walls of the house were splashed with blood.

In appealing against the convictions, Xie's lawyers argued he suffered a miscarriage of justice and that the expert evidence used to convict him was "unfairly prejudicial".

Robert Xie's wife, Kathy Lin, was in court for the decision.(ABC News: Luke Rosen)

Three of Xie's numerous appeal grounds related to a DNA sample found on the floor of his garage in May 2010.

The Crown case was that DNA from at least four of the victims was present in the sample, but Xie's lawyers argued it could have been DNA from several other living relatives, including his wife Kathy Lin.

They questioned comments on the DNA made at his trial by Crown expert witness, Dr Mark Perlin, saying Dr Perlin "strayed into the role of a jury" in his analysis of the DNA evidence.

Xie's appeal also included grounds that his barrister during his criminal trial let him down and that the trial judge misdirected the jury. 

In the New South Wales Court of Criminal Appeal, Chief Justice Tom Bathurst, Justice Hume and Justice Beech-Jones each dismissed the appeal.

Xie who appeared via video from jail, put his head in his hands after the judgment was delivered.

In the judgment, Chief Justice Bathurst said the court "did not accept that a miscarriage of justice occurred".

Xie's wife, who has always stood by him, made no comment outside court and refused to confirm if he would pursue the matter in the High Court.

His niece Brenda Lin, who was overseas on a school excursion when her family was murdered, was also in the public gallery but refused to comment.