By Liz Burke
The US police officer who shot Australian woman Justine Ruszczyk Damond dead is refusing to be interviewed by investigating authorities.
The Minnesota Department of Public Safety said in a statement Wednesday morning Mohamed Noor had "declined to be interviewed" by the state's Bureau of Criminal Apprehension.
The department confirmed Ms Damond died of a single gunshot wound to the abdomen, discharged by Noor.
While Noor has refused to offer his account of the Saturday night incident to authorities, his partner Matthew Harrity told the BCA what happened when the pair arrived at the scene in their squad car.
Harrity said he was "startled by a loud sound" as they approached the alleyway behind West 51st Street, where Ms Damond has called them.
"According to the BCA's preliminary investigation, officers Harrity and Noor responded to a 911 call from a woman now identified as Ruszczyk of a possible assault near her residence just after 11:30pm Saturday. Officer Harrity was driving. Officer Noor was in the passenger seat," the Department of Public Safety statement read.
"The officers drove south through the alley between Washburn and Xerxes avenues toward West 51st Street in search of a suspect. All squad lights were off.
"As they reached West 51st Street, Officer Harrity indicated that he was startled by a loud sound near the squad. Immediately afterwards Ruszczyk approached the driver's side window of the squad. Harrity indicated that Officer Noor discharged his weapon, striking Ruszczyk through the open driver's side window."
The officer told investigators he had seen a cyclist, described as an 18 - 25-year-old male, on the street immediately before the shooting. Harrity said the man stopped at the scene and watched on as officers provided Ms Damond with medical assistance.
Police are searching for this person, and any other witnesses to the incident.
Before Harrity's account of a being startled by a loud noise at the scene was released, an unidentified source with knowledge of Minneapolis law enforcement had told AAP fireworks could be related to the shooting.
The source said it "would be good common sense to investigate" whether the sound of fireworks going off in the area might have startled Officer Noor into opening fire.
A reference to fireworks is heard during the police radio conversations between Officer Noor, his partner Officer Matthew Harrity, the police dispatcher co-ordinating the emergency call and other officers rushing to scene. At one point the dispatcher asks for a precinct sergeant to acknowledge a report of "two shots heard from the east".
"We heard those sounds from the station," an officer responds. "Those are probably aerial fireworks."
Earlier it was reported Harrity was "stunned" when his colleague opened fire on the bride-to-be.
A police source told KARE11 Harrity was "stunned" when his partner opened fire, the Minneapolis news station reported.
Both men have been put on "paid administrative leave" by the police department after the Saturday night incident.
Officer Harrity, it has been revealed, had only been on the job for a year and his partner, Noor, had only two years experience as a police officer.
Noor was already being sued over an excessive force complaint, filed to the US District Court only three weeks before Damond's shooting.
Her death has been ruled a homicide.
Damond's grieving family has been damning of police over their handling of the shock incident.
Her frustrated husband-to-be Don Damond yesterday told media he had been given few details from authorities about why his fiancee was fatally shot.
"Sadly, her family and I have ben provided with almost no additional information from law enforcement regarding what happened after police arrived," he told reporters outside his home near where Ms Damond was gunned down.
Questions have also been raised over why the officers' body-worn cameras weren't turned on before the shooting. Their failure to record the incident is an apparent violation of the Minneapolis Police Department's policy.
Rules laid out in the Minneapolis Police Department's Policy & Procedure Manual specify that body worn cameras (BWC) are to be activated by police "prior to any use of force".
If the BWC has not been activated, it must be activated "as soon as it is safe to do so".
The manual states: "If there is a failure to activate the BWC in any of the above situations, the Officer shall document the reasons for the failure in the Officer's report or supplement."
Minneapolis police vehicles equipped with "mobile video recording equipment" in order to "capture video for criminal, civil and traffic-related court cases".
While the department has acknowledged cameras did not capture the incident, it is unknown whether cameras were not functioning properly, if they were working but had been switched off, or if the officers involved intentionally or unintentionally failed to activate them.
The department's internal affairs process will determine whether a law enforcement agency policy was broken, the state's Bureau of Criminal Apprehension has said.
Damond's family both in the US and in Australia have said they are desperate for answers.
A dawn vigil has been held at Sydney's Freshwater Beach where people gathered to pay tribute to Damond and support her family.
The crowd, led by Damond's father John Ruszczyk, paid silent tribute to the passionate yoga and meditation teacher and life coach, who was originally from the area.
Prime Minister Malcolm Turnbull has this morning committed to seek answers for the family.
"This is a shocking killing. It is inexplicable," he told the Nine Network.
"How can a woman out in the street in her pyjamas, seeking assistance from police be shot like that? It is a shocking killing, and we are demanding answers on behalf of her family."
'It's not a big crime, right? I'm saving a child mate.'