Police have been waiting to receive medical clearance from doctors at a Brisbane Hospital before the officers could interview the Samoan.

Acting Commissioner of Police, Peter Marshall, said that the investigation has been very comprehensive and he expects it to be finalised next week.

"Police have spoken to dozens of witnesses in this investigation. Obviously the Samoan officer who is in Brisbane receiving medical treatment is a key witness and he will be interviewed in the coming days.

"Once the officer returns from Brisbane and the investigation is finalised, a complete brief of evidence will be given to the Director of Public Prosecutions for his consideration," he said.