A Minnesota prosecutor has convened a grand jury in the police shooting of Australian woman Justine Damond.

Key points: Mohamed Noor's partner receives grand jury subpoena in relation to Justine Damond shooting

Mohamed Noor's partner receives grand jury subpoena in relation to Justine Damond shooting Hennepin County Attorney Mike Freeman previously said he did not have enough evidence to charge Mr Noor

Hennepin County Attorney Mike Freeman previously said he did not have enough evidence to charge Mr Noor Ms Damond was shot while reporting a sexual assault outside her house

She was shot by Mohammed Noor in Minneapolis in July 2017, in the lead-up to her wedding.

Hennepin County Attorney Mike Freeman said previously he would no longer use grand juries in police shootings, and would decide those cases himself.

Fred Bruno, the lawyer for Mr Noor's partner Matthew Harrity, told the Star Tribune that Mr Harrity got a grand jury subpoena on Wednesday (local time).

Mr Freeman's office said in a statement it could not comment on grand juries because they were secret, but that Mr Freeman would be the one to decide on charges.

Minneapolis police officer Mohamed Noor shot Justine Damond in July 2017. ( Star Tribune: City of Minneapolis )

In December, Mr Freeman was recorded telling activists that he did not have enough evidence yet to charge Mr Noor and investigators had not done their jobs.

He apologised for those comments but said he believed it was his responsibility to talk to constituents, but it was wrong to discuss the agency's work.

He said at the time he had not yet decided whether to charge Mr Noor.

"I've got to have the evidence. And I don't have it yet. And let me just say, it's not my fault," he said.

"So if it isn't my fault, who didn't do their jobs? Investigators. And they don't work for me. And they haven't done their job."

Ms Damond, 40, was shot dead while she was unarmed and wearing her pyjamas outside her home in Minneapolis.

The former Sydneysider was home alone the night she died and was working in her lounge room when she heard what she thought sounded like a sexual assault in the laneway behind her house.

She phoned her fiance, Don Damond, and they agreed she should call 911.

When the police squad car arrived and drove down the laneway, she left the house to approach the officers in the car and was shot.

Ms Damond's family said in a statement it was, "happy that the Hennepin County attorney is using every means at their disposal to get people to cooperate in this investigation".

"It appears there has been a reluctance on the part of a number of officers, so we are happy that they will suffer the penalties of perjury if they lie to the grand jury," the family said.

Ms Damond's family previously questioned the integrity of the investigation into her death.

Her father, John Ruszczyk, said last month, "we are deeply concerned that the initial investigation was not done properly and with the greatest of integrity and sense of completeness".

Mr Ruszczyk said in the days after his daughter's death he spoke to BCA officials who "promised a complete and rigorous investigation of Justine's shooting".

"These officers spoke of their sympathy for our loss," he said.

"They also promised a complete and rigorous investigation of Justine's shooting.

"They assured us that they would give the County Attorney all the necessary information to make a reasoned decision on whether or not to charge Justine's shooter with a crime."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 2 minutes 17 seconds 2 m 17 s Justine was shot at the end of a laneway which runs behind her house in South Minneapolis.

AP/ABC