The Mayor of Minneapolis, where an Australian woman was shot dead by police, said she is disappointed that the junior officer won't agree to be interviewed by investigators.
Justine Ruszczyk Damond was fatally shot in the stomach by Minneapolis police officer Mohamed Noor on Saturday night after she called 911 to report an assault.
Mayor Betsy Hodges said she wishes she could make the young officer, who has just 21 months experience, speak.
"We cannot compel Officer Noor to make a statement, I wish we could, I wish that he would make a statement," she told media.
The Minnesota Department of Public Safety Bureau of Criminal Apprehension (BCA) confirmed they interviewed officer Noor's partner, Matthew Harrity who has just 12 months experience.
But Noor himself has declined their request for an interview.
"Officer Noor’s attorney did not provide clarification on when, if ever, an interview would be possible," the BCA said in a statement.
"Under the law, the Bureau of Criminal Apprehension cannot compel the testimony of either officer."
- Family and friends remember Justine at sunrise vigil
- Cop may have been spooked by fireworks
- Aussie victim tells of overcoming her 'dark side'
- The US cop 'who shot dead Australian woman in her pyjamas'
- Why were police body cams switched off during fatal shooting of Australian woman?
Investigators seek key witness
Investigators are also searching for a man who was riding a bike past the two police officers moments before the shooting.
Officer Harrity told investigators that he saw an “18-25 year old white male who was bicycling eastbound on West 51st Street immediately before the shooting”.
“This individual stopped at the scene and watched as the officers provided medical assistance to Ruszczyk,” a statement from the Minneapolis police department said.
“BCA agents would like to speak with this person and anyone else who may have witnessed the incident.”
Mayor Hodges said she "would implore this person to come forward".
She said she shares the frustration and dismay that neither officer had their bodycameras switched on.
The investigators' statement added that no weapon was found at the scene, just a mobile phone.
The BCA investigators will turn their findings over to the county attourney but are awaiting the results of forensic testing.
Separately the Minneapolis police Departement is carrying out an internal review of the officers' actions. Both officers have been placed on leave.
Meanwhile Malcolm Turnbull says Australia is demanding answers on how the former Manly resident was shot dead in her pyjamas.
As Sydneysiders gather to pay tribute to Justine Damond, the prime minister said Australia's consul-general is supporting the family.
"It is inexplicable. Our hearts go out to her family," he said.
"How can a woman out in the street in her pyjamas seeking assistance from the police be shot like that? It is a shocking killing."