The US police officer who shot dead Australian woman Justine Ruszczyk plans to plead not guilty to murder and manslaughter charges.

According to court documents filed on Wednesday in Minneapolis, Mohamed Noor intends to use self-defence and reasonable force in his defences, The Star Tribune reports.

The Rule 9 disclosure document, signed by Noor’s attorney Thomas Plunkett, did not elaborate further.

(Supplied)

Noor was charged on March 20 with third-degree murder and second-degree manslaughter in the July shooting death of 40-year-old Ruszczyk.

Noor was released on US$400,000 (A$516,000) bail on March 22 after his first court appearance over the shooting death of Ruszczyk.

Noor is accused of shooting Ruszczyk, a life coach from Sydney's northern beaches, minutes after she called 911 to report a possible sexual assault in the alley behind her home in July last year.

Hennepin County Attorney Mike Freeman said Noor acted “recklessly” when he fired the shot into the dark that killed Ruszczyk.

The shot came after Noor and his partner, Matthew Harrity, had driven through the alley behind Ruszczyk’s home and were about to leave when they were surprised by someone outside the police car.

The driver of the car, Harrity, has told investigators he was “spooked” and did fear for his life, taking his gun from its holster before Noor reached across and fired his weapon out the driver’s side window.

(AAP)