An expert in biomechanics has testified that an Aboriginal teenager shot dead by police in 2019 posed a "low-threat" at the time the fatal bullets were fired.
Constable Zachary Rolfe was attempting to arrest Kumanjayi Walker in the remote Northern Territory community of Yuendumu in November 2019 when the 19-year-old struck him in the shoulder with a pair of scissors.
While Rolfe's colleague Sgt Adam Eberl wrestled with the teenager, Rolfe drew his Glock pistol and fired three times. Kumanjayi Walker later died of his injuries.
Constable Rolfe has pleaded not guilty to murder and alternative charges resulting from the second two gun shots. The first has been deemed a 'reasonable use of force'.
Dr Andrew McIntosh was called to give evidence in biomechanics, the science of creating force with, and the effects of force on, the human body.
He wrote three reports on the fatal shooting and examined the body-worn camera vision, images of the injuries, scissors and the clothing of Constable Rolfe and Constable Eberl.
He told the court that while the two officers struggled with Kumanjayi Walker there was a threat to both of them, but “as they were separated the threat diminished.”
Biomechanics expert Dr Andrew McIntosh testified in court Friday. Source: NITV
After Constable Rolfe fired the first shot, Constable Eberl wrestled Kumanjayi Walker down on to a mattress, where body-worn vision appears to show the 95kg officer partially pressing his weight onto the teenager.
At was at this point that Constable Rolfe fired the second and third shots at close range.
“Mr Walker was unlikely to be a direct threat to Officer Rolfe at the time of the second and third gunshots," testified Dr McIntosh.
“[He was] a low threat to Constable Eberl at the time of the second and third gunshots."
Dr McIntosh told the court that the human torso accounts for approximately half a human's weight, and that consequently a "large proportion" of the officer's body mass was pinning Kumanjayi Walker's right arm, which held the scissors, underneath him.
"About 45kgs [was] pushing down through Kumanjayi Walker’s chest, and his right arm.
“It limits by half the amount of movement of your arm, you’re not really able to thrust with your hand, and makes it difficult to develop force if you are holding a weapon."
Constable Rolfe’s barrister David Richardson QC, who has focused much of his defence on the "limitations" of body-worn camera vision, asked Dr McIntosh if the scissors can be seen in any of the videos until “after all three shots have been discharged.”
Constable Adam Eberl was positioned partially on top of Kumanjayi Walker when the teenager was shot. Source: Supplied
“I could not see any conclusive evidence of the scissors up until that point of the video," Dr McIntosh confirmed.
He also conceded that “you cannot see Mr Walkers right forearm or arm when Mr Eberl is on top of him.”
Mr Edwardson said Dr McIntosh had the "luxury" of examining the body-worn vision of both officers frame by frame and second by second, unlike the officers who had to make a split-second decision in real time.
“What ever opinion you have expressed as to the threat, and whether it was low or not, must be seen in that light?" asked Mr Edwardson.
"I agree with that, yes," replied Dr McIntosh.
Final witnesses called next week
Queensland forensic pathologist Dr Paul Botterill also gave evidence Friday.
He was questioned about his opinion as to whether the scissors had the capacity to inflict a serious or potentially fatal wound to a police officer, given the position of Kumanjayi Walker during the attempted arrest.
“If the limb was not able to freely move, then the only way that an implement such as those scissors could have resulted in a serious life-threatening injury would be if there was movement of the other party, the police officer, up against that immobilised weapon," testified Dr Botterill.
“And it’s very unlikely... to result in a potentially fatal injury."
Prosecutor Philip Strickland SC told Justice John Burns and the jury that he has several more witnesses to call, but expects to wrap up the crown case against Constable Rolfe early next Tuesday.
The defence team responding by saying they are yet to decide whether they will give evidence ahead of closing addresses by both sides.
