The identity of a Tauranga man who killed a 14-week-old baby boy can now be revealed.

Name suppression has been lifted from Surender Singh Mehrok, 21, who was convicted of murdering Richard Royal Uddin, whose skull had been "cracked like an egg" after an assault in June 2016.

Richard suffered multiple skull fractures and the forensic evidence was consistent with his head hitting a carpeted floor with significant force, similar to a high speed car crash.

Mehrok, who was 19 at the time, admitted causing the fatal injuries but denied he meant to kill the baby.

But he was found guilty of murder after a trial in the High Court at Tauranga last July and will serve at least 14 years and 6 months of a mandatory life sentence.

Name suppression has been lifted from Surender Singh Mehrok who was convicted of murdering Richard Royal Uddin. Photo/George Novak

In sentencing Mehrok last August, Justice Mary Peters accepted Mehrok had not meant to kill Richard but must have known assaulting a defence 14-week-old baby was likely to cause his death.

"Richard Uddin was a lovely little baby and his death is tragic for everyone," said Justice Peters. "No one but you knows precisely what happened but Richard's injuries tell a powerful story."

Mehrok was in a casual relationship with Richard's mother Nikita Winiata and was babysitting on the night he inflicted the fatal injuries.

She was left "heartbroken" by her son's death, suffered nightmares and turned to drugs and alcohol to numb her pain, according to her victim impact statement read to the court.

"I will never hear Richard say 'I love you mum' and have a hug. This is every parent's dream, which as been taken away from me," the grieving mother said.

"I feel Richard has been wiped out of our lives...and I fear the way he died, he must have been in pain which no child of any age should experience."

Mehrok has appealed the murder conviction - arguing it was manslaughter - but no date has been scheduled for a hearing in the Court of Appeal.

He had no previous convictions.

The guilty verdict on the murder charge means the jury accepted the Crown case that even if Mehrok didn't mean to kill Richard, he knew the assault was likely to lead to his death.

The Herald has obtained the medical evidence presented to the jury, including x-rays and 3D modelling, of the injuries suffered by the infant.

Several CT scans and post mortem examination showed Richard suffered multiple fractures to the back of his scalp and both sides of his skull, as well as several brain lacerations.

Dr Vivienne Hobbs, who tried to resuscitate Richard after he was taken to Tauranga Hospital by his mother, said significant force, similar to a high-speed car crash, would be needed to cause such injuries.

"Either the baby's head impacted on something or something impacted with the boy's head."

Another expert, pathologist Dr Dianne Vertes, told the jury these types of injuries would have been most likely caused by the baby's head hitting a hard surface.

CT scans show the multiple fractures which caused the death of baby Richard Uddin. Photo / Supplied

Dropping Richard on the floor, or accidentally bumping his head on the wall, would not cause these types of injuries, said Dr Vertes.

"This is a violent force. This is significant force which is the better word."

A third expert, paediatric radiologist Dr Russell Metcalfe said there were multiple fractures revealed in the CT scans and 3D imaging of the baby's skull.

As well as depression fractures, "gross" brain swelling and significant bleeding, there were lots of smaller fractures. "Too many to count," Dr Metcalfe told the jury.

He had seen many head injuries caused by blunt force trauma during his 23 years at Starship Hospital and ranked Richard's injuries in the "severe" category.

"This was no accident," Crown Solicitor Anna Pollett told the jury in her opening address. "This was an extreme amount of force inflicted on a defenceless 14-week-old.

"[The defendant] completely lost it...and he assaulted Richard Royal with the intent to kill him, or diced with the risk that it would cause his death."