A scenario put forward by a man accused of murdering a six-month-old baby at New Lambton in 2019 was "entirely possible" as an explanation for the fatal injuries, a jury has been told.
Specialist forensic pathologist Professor Johan Duflou on Thursday gave evidence for the defence during the Newcastle Supreme Court trial of Jie William Smith.
The 31-year-old has pleaded not guilty to murdering his then partner's six-month-old son, who went into cardiac arrest at Mr Smith's unit at New Lambton in the early hours of February 9, 2019.
The prosecution has rejected Mr Smith's guilty plea to manslaughter on the basis that he failed to seek medical attention after witnessing the mother seriously injure the baby.
Defence barrister Paul Rosser, QC, asked Professor Duflou to assume the accuracy of Mr Smith's version of what happened, which began with the mother picking up the crying baby about 2am.
The woman, who denied the allegations in her evidence, was then said to have punched the baby in the face and chest twice each with the side of her hand, before vigorously shaking him four or five times.
The baby was then said to be bleeding, have had dim eyes, fractious and unsettled, refusing to eat and would just take a sip or two from the bottle.
Mr Rosser then asked Professor Duflou to assume that at about 4.15am, Mr Smith was holding the child and a bottle, when the baby suddenly went backwards out of his arms and landed on the floor.
Asked how this version fitted in with the presentation of the child's condition when taken to hospital, Professor Duflou replied "yes, it is entirely possible".
He said an earlier shaking and punching of the child could have led to a deterioration in brain functioning and a condition that included seizures which could be a reason why the baby fell out of the man's arms.
Under cross-examination from Crown prosecutor Neil Adams SC, Professor Duflou agreed all of the baby's injuries could have been caused at the same time.
Justice Helen Wilson asked Professor Duflou if he accepted the version about the 2am incident, could he say what the outcome would have been if the child was then immediately taken to hospital.
"It is difficult to say," he replied. "Potentially the child may still have died, although I could not say with any degree of certainty. "The longer you wait the more dangerous these abnormalities become."
Mr Smith gave evidence earlier in the week, claiming he initially lied to police about the injuries to protect the child's mother despite admitting the pair only had a casual relationship.
