Police officers shot a kangaroo injured in a collision with a police van four times without killing the animal on Thursday night, before leaving it by the side of the road and driving off, with a ranger arriving two hours later.
Photographs seen by The Canberra Times show the kangaroo alive with multiple bullet wounds to the head and a broken leg.
A police spokesman said the officers were required to shoot the kangaroo for "compassionate reasons".
"The RSPCA has examined the circumstances surrounding the incident. No offences were identified and no further action will be taken by the RSPCA," he said.
Another photograph shows three police officers shining a torch at the kangaroo, which was lying on its side in nature strip beside Tharwa Drive.
A police spokesman said the incident would be reviewed to ensure it complied with firearm safety orders that allow police officers to use firearms to kill injured or dangerous animals.
Shane Berger, whose house backs on to the suburban nature strip where police shot the kangaroo, said the police officers had hit the kangaroo with a police van on Tharwa Drive about 6.15pm, south of the intersection with Drakeford Drive.
"The ranger didn't end up getting there until about 8.15pm, so this poor roo was sitting there suffering the whole time," he said.
A spokeswoman for the RSPCA said the organisation received several reports of the incident and had met with the police.
"As there was no breach of the current animal welfare legislation, there was nothing legally that we could further do.
"We did however pass on some advice to the AFP and were informed that they would be looking into their processes internally."
Mr Berger said the police van was significantly damaged. The passenger door was difficult to open and the officers had to collect plastic panelling from the road.
"I was sitting up on the fence watching the whole thing and next thing I know, they've got the torch there and checking on it and stuff, and next thing you know, one officer is pulling out his weapon and shooting it," he said.
"He shot it, its head hit the ground, five seconds later its head comes up. The three of them are looking at each other and wondering what's going on."
Mr Berger said the officers walked off and then came back and the shot the kangaroo another three times.
He offered the police officers a knife to slit the kangaroo's throat. "I said, 'The poor thing's going to die of lead poisoning before you do anything decent here'," Mr Berger said.
Mr Berger said he reported the injured kangaroo to Access Canberra. An operator told him that a ranger had been unable to find the animal where police reported it and would be sent out again.
The Environment, Planning and Sustainable Development Directorate confirmed an on-call ranger attended and euthanised the injured kangaroo.