A child abuse specialist admits his opinion on the health of the Kahui twins before the first evidence of them being unwell depends on witnesses telling the truth.
Dr Patrick Kelly made the admission while under cross-examination at the trial in the High Court in Auckland of ChrisKahui, 23, who is charged with murdering his premature three-month-old twins Cru and Chris in June 2006.
Kahui's lawyers said somebody else, probably the twins' mother Macsyna King, killed them. The Crown says Kahui was the only person who could have inflicted the injuries, and that Ms King was absent when they were hurt.
The Crown argument is that the babies received their fatal injuries about 8.30pm-9pm on June 12 2006, when an episode where Kahui gave Cru CPR showed he was very unwell.
Dr Kelly said evidence from April Saunders, who fed the twins about noon that day, suggested the babies fed well and were in good health.
Ms King also gave evidence that the babies were normal prior to her leaving the house that day, evidence Dr Kelly said was important when he made his judgment.
"My opinion is completely dependent on the caregiver telling me the truth. That would apply to all the other witnesses," Dr Kelly told Kahui's lawyer Michelle Wilkinson-Smith.
He said his opinion would be affected if the witnesses lied or were mistaken.
Dr Kelly said he held a different opinion on timing of the injuries to Dr Terence Donald, an Adelaide child abuse expert who is due to give evidence for Kahui's defence team.
He said he knew Dr Donald believed the CPR incident about 9pm on June 12 came some time after the Cru received his brain injuries because there was no tissue damage to the cervical spinal cord.
However, he said the severity of the brain injuries Cru had suggested he would have been very unwell immediately after they were sustained or within a few minutes.
"The severity of the primary injuries are such that I do not believe that after that brain injury they would have returned to anything remotely close to a normal state."
The Crown case is due to finish within the next few days. Kahui's lawyers are expected to open their case tomorrow. The case is expected to last another two weeks.
