Troy Taylor, the de-facto stepfather of Christchurch infant Ihaka Stokes, has today been found guilty of the boy's brutal murder.

LISTEN ABOVE: Newstalk ZB reporter Chelsea Daniels has been at the trial and spoke to Jack Tame on Larry Williams Drive

Troy Kevin Taylor, 23, had denied murdering the 14-month-old boy during a two-week trial at the High Court in Christchurch.

He claimed that his then-partner and Ihaka's mother Mikala Stokes inflicted the boy's 59 fatal injuries on July 3, 2015 while he was out getting a tattoo.

But after four hours of deliberations, a jury of six women and six men were unanimous in finding Taylor guilty of murder.

They also found him guilty of assaulting the child the day before the murder.

Taylor mouthed "no" as the verdicts were read out today, while family members in the packed public gallery said "no way".

He will be sentenced on June 9.

As he was led into custody, Taylor quietly said, "f****** b*******".

Justice Cameron Mander thanked the jury for their service.

The Crown had alleged that Taylor was suffering from sleep deprivation, headaches, and irritability caused by multiple concussions around the time Ihaka was developing an ear infection, when he "snapped".

After eight days of evidence, both the Crown and Defence gave their closing addresses yesterday.

Justice Mander summed up the evidence and told the jury that they must remain unaffected by emotion when reaching their verdict.

The judge brought up the issue of Taylor lying to police and others.

He said that just because Taylor lied, it didn't necessarily make him guilty.

Justice Mander said people in those kinds of circumstances can lie for all kinds of reasons.

The court heard how Taylor told police just minutes after the boy's death at the couple's Truman Rd home how he heard two "bangs" in the night and thought he'd fallen in his cot.

Giving evidence, Taylor said he lied to police about the fall to protect the heavily-pregnant Stokes.

He testified to say that Ihaka was floppy and breathing raspily when he got into the child's cot earlier in the evening.

Worried that Stokes had done something, he baulked at getting medical help because he didn't want to get her into trouble.

He claimed he would've "gone to prison" for her if she'd admitted hurting Ihaka in a four-hour window that he was out of the house.

But Crown prosecutor Mark Zarifeh said in his closing address that the medical evidence heard in the trial - which Taylor dismissed, saying "science gets lots of things wrong" - completely undid his story.

UK neuropathologist Professor Colin Smith believed it was a "maximum of minutes" from the time Ihaka received his injuries before he became unconscious.

Asked to comment on defence suggestions that Stokes inflicted the injuries in the afternoon - at least three hours before Taylor says he found him unresponsive in his cot - Smith replied: "That is not an explanation for the pathology that is present in this case."

Zarifeh said the medical evidence was not consistent with Taylor's account, and also independently showed that Stokes couldn't have inflicted the injuries on the Friday afternoon.

Taylor lied to police that fateful night, Zarifeh said, not to protect Stokes, "but to protect himself".

The Crown said it was a case that involved a "momentary snapping", in what was "a reckless killing... and in our law, that's murder".

Ihaka died in hospital from what is agreed was non-accidental, violent injuries, including broken bones and severe brain damage.

Defence counsel Phil Shamy reminded the jury, who have repeatedly seen disturbing images of Ihaka's bruised dead body from his post-mortem, to put aside any feelings of prejudice and sympathy.

"This young man is on trial for probably the most serious charge anyone can face - the murder of a child ," Shamy said in his closing address.

"This is a court of justice, not of emotion. You must be so careful in this trial."

Shamy accused police of "investigative bias" after Ihaka's death, claiming they had "made up their mind right at the beginning" that Taylor was responsible.

He said police appeared to have accepted almost immediately what Stokes told them, yet they pushed Taylor to confess.

On the night Ihaka died, Stokes was asked by police if she had harmed him.

She replied, "I don't know", and said she had a history of sleepwalking.

Later, when police pressed her further she denied any involvement in his death.

During the trial, she again repeatedly denied inflicting his injuries.

Shamy told the jury that the onus was on the Crown to prove beyond reasonable doubt who killed Ihaka.

"Mr Taylor proves nothing... you've got to be sure. Sure it wasn't Mikala Stokes and sure it was him," Shamy said.

"If you're not sure, you've got to give Mr Taylor the benefit of the doubt.

"You cannot convict Mr Taylor by default, just because he's the only one sitting here."