The mystery behind why Australian bride-to-be Justine Damond was shot dead by police outside her Minneapolis home could be explained by the explosions of fireworks in her neighbourhood.

A source with knowledge of Minneapolis law enforcement, who asked not to be identified, told AAP on Tuesday it 'would be good common sense to investigate' the fireworks link.

The sound of fireworks may have startled Officer Mohamed Noor, the policeman who fired the fatal bullet to the 40-year-old spiritual healer's abdomen.

The fireworks link came as it was revealed Noor's partner was 'stunned' when the rookie cop opened fire through the squad-car door at Damond, who had approached the car, dressed in pyjamas.

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The mystery behind why Australian bride-to-be Justine Damond (pictured) was shot dead in her pyjamas outside of her Minneapolis home could be explained by the possible setting off of fireworks

Mohammed Noor (pictured) shot Justine Damond from the passenger seat of his squad car while she spoke to his colleague, who is said to have been 'stunned' by his partner's actions

Officer Matthew Harrity, who was in the driver's seat, was speaking to Ms Damond after she called 911 to report a sexual assault occurring near her home, when Nor reached across him and shot her.

A police source told KARE11 that Harrity was 'left stunned' by officer Mohamed Noor's actions.

A reference to fireworks can be heard during the police radio conversations between Officer Noor, Officer Matthew Harrity, and 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.'

The independent Minnesota Department of Public Safety Bureau of Criminal Apprehension, not the Minneapolis Police Department, is investigating the shooting and revealed on Wednesday that Noor has refused to be interviewed.

'Officer Noor has declined to be interviewed by BCA agents at this time. Officer Noor's attorney did not provide clarification on when, if ever, an interview would be possible,' the BCA said in a press release on its website on Tuesday night (Wednesday morning in Australia).

Although there are still many unanswered questions, the BCA revealed an outline of the incident.

The BCA said Officer Harrity told authorities the men had heard a 'loud sound' near the squad car as they approached the scene without their emergency lights on.

Immediately after Ms Damond approached his driver's side.

'Harrity indicated that Officer Noor discharged his weapon, striking Ruszczyk through the open driver's side window,' authorities said.

The BCA said they there is no video or audio footage of the incident.

Noor and Harrity have been placed on administrative leave.

Noor, 31, has offered his 'condolences' but demanded everyone respect his privacy after opening fire on the 40-year-old yoga instructor. He has hired an attorney.

Minneapolis Mayor Betsy Hodges said she wished Noor would consent to an interview.

'We can't compel him by law, but I wish that he would make that statement. There are big questions left that we still have and that we hope to have answered soon.

'Why did Officer Noor draw and fire his gun? What happened from the time the officers arrived on the scene to when she was pronounced dead? Why don't we have footage from body cameras? Why were they not activated? We all want answers to those questions.'

The grieving family and friends of Justine Damond gathered at dawn on a Sydney beach for a moving and deeply spiritual silent vigil (pictured is Ms Damon's father John Ruszczyk weeping during the vigil)

Hundreds of mourners quietly lit candles on the shore of Freshwater Beach as the sun began to rise on Wednesday morning

Just before 7am after a period of meditation and many tears, close friend 'The Gong Guru' Matt Omo performed a didgeridoo piece to honour the beloved spiritual healer and life coach (pictured)

The BCA called for a male witness, aged between 18 and 25, who was cycling past the scene after the shooting and watched as the two police officers tried to resuscitate Ms Damond.

The transcript of Ms Damond's 911 call for help is expected to be released soon, Minnesota city attorney Susan Segal said during a press conference.

Hennepin County Attorney Mike Freeman told 9News on Wednesday Noor could face a murder charge because Ms Damond's death has been ruled a homicide.

A charge of second-degree manslaughter is more likely, he said.

'In Minnesota normally it's a charge of second degree manslaughter,' Mr Freeman said.

'[But] it's way too premature for us to make that call yet.'

Mayor Betsy Hodges and Assistant Police Chief Medaria Arradondo address the latest developments in the death of Justine Damond on Tuesday

Mr Freeman, who previously argued that the police officer's body cameras should have been turned on at the time, said his office has yet to speak to the officers.

When asked if Noor and his partner were cooperating with authorities, Mr Freeman answered 'no and yes.'

'Well, we are hoping that in the very near future they will talk. But until they do, we don't know. An independent investigation is currently underway to determine how and why Justine was killed,' he said.

Ms Damond's heartbroken family gathered on Sydney's northern beaches on Wednesday morning for a silent vigil in her honour, and Australia's Prime Minister Malcolm Turnbull demanded answers on how she was killed.

'It is inexplicable. Our hearts go out to her family,' he told 9News on Wednesday.

'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.'

As the morning sun dipped above the horizon, people lowered flowers - mostly coloured pink, Justine's favourite colour - into the ocean (pictured front is her father John Ruszczyk hugging wife Maryan)

Justine's brother Jason is seen being consoled by his wife while he placed flowers in the water

The crowd began to gather around 6am on Wednesday morning

Hundreds of mourners, including Justine's dad John and his wife Maryan Herffernan, quietly lit candles on the shore of Freshwater Beach, in New South Wales, as the sun began to rise on Wednesday.

Just before 7am after a period of meditation and many tears, close friend 'The Gong Guru' Matt Omo performed a didgeridoo piece to honour the beloved spiritual healer and life coach, lamenting her 'generosity of heart and spirit' that was 'shared with so many.'

As the morning sun dipped above the horizon, people lowered flowers - mostly pink, Justine's favourite colour - into the ocean.

A man played the violin as pink roses scattered the shoreline, with many staying to watch the waves lap at the beach - not far from Justine's family home where she was born and raised.

As mourners began to leave the beach, Mr Ruszczyk and his wife Maryan, remained by the water, embracing each other and sobbing.

The vigil, which was explicitly billed as a silent event, described Ms Damond as an 'extraordinarily kind, funny, smart and loving woman.'

A timeline shows the events that led up to the fatal shooting of Justine Damond at around 11.30pm on Saturday

Pride: This picture dates from 2015 and shows Officer Noor (right) being inducted into the Somali American Police Association

The Minneapolis cop who shot dead bride-to-be Justine Damond through a squad car door (pictured is a computer generated reenactment of the incident) 'offers condolences'

Meanwhile, the Mayor of Minneapolis Betsy Hodges is demanding to know why neither officer had their bodycam turned on at the time, which she called a 'key question' for investigators.

Autopsy results by the Hennepin County Medical Examiner revealed Damond died from a gunshot wound to the abdomen and classified her death as a homicide.

The chilling moments directly after she was killed were captured on an audio exchange between dispatch and the officers involved, on the website Minnesota PoliceClips.

The call begins just before 11.28pm on Saturday night, when an officer can be heard saying there is a 'female screaming behind the building'.

The officer says they are performing CPR after 'shots fired and one down' and call for other units, including medical, to come to 'Code 3, Washburn and 53rd St'.

STATEMENT FROM POLICE OFFICER MOHAMED NOOR 'Officer Noor extends his condolences to the family and anyone else who has been touched by this event. He takes their loss seriously and keeps them in his daily thoughts and prayers. 'He came to the United States at a young age and is thankful to have had so many opportunities. He takes these events very seriously because, for him, being a police officer is a calling. He joined the police force to serve the community and to protect the people he serves. Officer Noor is a caring person with a family he loves and he empathizes with the loss others are experiencing. 'The current environment for police is difficult, but Officer Noor accepts this as part of his calling. We would like to say more, and will in the future. At this time, however, there are several investigations ongoing and Officer Noor wants to respect the privacy to the family and asks the same in return during this difficult period.' Advertisement

'No suspects at large,' the cop told the dispatcher after around a minute.

Mayor Hodges is asking why the officers' cameras - which could have provided clear evidence to the events that unfolded that night - were off.

'You know, I fought hard to make sure that we have body cameras, she told GMA. 'They're a very powerful tool, they're not an infallible tool, but they're an important tool in 21st century policing and I don't know why they weren't turned on.

'I don't know what happened. That's one of the key questions that we have as the investigations move forward.'

Police in Minneapolis are required to wear bodycams at all time, but they are not continually active and are manually switched on when an officer anticipates they will be needed. It is not known why the dashcam cannot be used in this case.

The decision to equip all police with bodycams came after the motorist Philando Castile was shot by an officer in 2016 in controversial circumstances.

The Mayor, who previously posted on Facebook she 'wanted to take a moment to recognize Officer Mohamed Noor, the newest Somali officer in the Minneapolis Police Department', demanded fast answers as the investigation began on Monday.

Mayor of Minneapolis Betsy Hodges (pictured) said a 'key question' for investigators was why the cops' body cameras were off

JUSTINE DAMON'S SHOOTING: WHAT WE KNOW AND WHAT WE ARE WAITING FOR What we know Justine Damon, 40, an Australian living with her American fiance in Minneapolis, called the police to report a sexual assault in the alley near her home. Officers Mohamed Noor and Matthew Harrity arrived at the property on Washburn and 53rd St, Minneapolis, Minnesota, before 11.30pm on Saturday. Justine Damon, 40, an Australian living with her American fiance in Minneapolis called the police to report a sexual assault in the alley near her home (pictured is her home and the alley that runs alongside it) Officers Mohamed Noor and Matthew Harrity arrived at the property on Washburn and 53rd St, Minneapolis, Minnesota, (pictured) before 11.30pm Neither of the officers switched on their body cameras. Harrity, the squad car driver, was speaking to Damon who was stood outside the car window when Noor leaned across him and opened fire. Noor shot multiple times, hitting Damon once in the abdomen. She died at 11.51pm from the gunshot wound, the autopsy revealed. Harrity was reportedly 'stunned' by his partner's actions. Both cops have been placed on administrative leave. The investigation is being conducted by a state agency, the Bureau of Criminal Apprehension, rather than internally by Minneapolis police. There were no weapons recovered from the scene of the shooting. What we don't know It is still unclear why Noor shot the unarmed woman. While some had theorized he may have perceived the meditation instructor as a threat to his partner, Harrity's surprised reaction, according to sources, makes that less likely. The BCA are handling the investigation as part of an agreement made in 2014 so the Minneapolis police don't investigate themselves in sensitive 'critical incident' cases, aimed at bolstering trust in the police. Harrity was interviewing Damond, when Noor reportedly reached across him and shot her (cops at the scene after the shooting) One of the officers called dispatch for emergency medical crews but Damond died at just before midnight (crime scene teams at the site of the shooting) Therefore, Minneapolis police and the city do not have information on the current investigation, according to the Mayor who called the lack of information 'frustrating.' The BCA say they are examining the evidence and are working with the officers' attorneys to schedule interviews. Only once the interviews are complete, will they release more information on how and why the shooting occurred. Once their investigation is complete, they will present their findings to a county attorney. It is also unclear why the officers never turned on their bodycams. Procedure dictates the cameras are supposed to be turned on prior to use of force, during 'any contact involving criminal activity', and 'during their shift at all times when they could reasonably anticipate that they may become involved in a situation for which activation is appropriate in accordance with this policy.' This will likely be a question posed by the BCA investigators. Advertisement

'I have the same questions you do, and I seek the same answers you seek,' said Mayor Hodges.

'This process is difficult, but I want to be sure we get this right.'

Police Chief Janeé Harteau told CNN she has called for the investigation 'to be expedited to provide transparency and to answer as many questions as quickly as we can.'

On Monday, Justine's fiance Don Damond said the family were 'desperate for information' about her shooting - which he referred to as a homicide.

Her heartbroken father John spoke for the first time on Tuesday afternoon, describing their shock at their daughter's death and calling on 'the light of justice to shine down'.

'We thought yesterday was our worst nightmare but we awoke to the ugly truth and it hurt even more,' an exhausted John Ruszczyk said, flanked by his wife.

'Justine, our daughter, was so special to us and so many others. We went down to Freshy (Freshwater) beach this morning and saw the blackness turn to light.

'Justine was a beacon to all of us, we only ask that the light of justice shine down on the circumstances of her death.'

Don Damond, fiance of an Australian woman shot dead by police after she called 911 to report a sexual assault happening in the alley behind her home, fought back tears as he claimed that the cops have failed to provide any explanation

Don Damond, Ms Damond's fiance, was comforted by a friend after addressing the media

John Ruszczyk (pictured), the heartbroken father of Justine Damond, has called for the 'light of justice to shine down' on the mysterious death of his daughter at the hands of U.S. police

Noor, 31, was the first Somali-American officer in his precinct.

In a statement released by his attorney, the officer said he takes the family's loss 'seriously and 'keeps them in his daily thoughts and prayers'.

'He came to the United States at a young age and is thankful to have had so many opportunities. He takes these events very seriously because, for him, being a police officer is a calling. He joined the police force to serve the community and to protect the people he serves. Officer Noor is a caring person with a family he loves and he empathizes with the loss others are experiencing,' the statement read.

'The current environment for police is difficult, but Officer Noor accepts this as part of his calling. We would like to say more, and will in the future.

'At this time, however, there are several investigations ongoing and Officer Noor wants to respect the privacy to the family and asks the same in return during this difficult period.'

Mr Damond, who addressed the assembled media from his backyard in Minneapolis, said 'piecing together Justine's last moments before the homicide will be a small comfort as we grieve this tragedy.'

'Our hearts are broken and we are utterly devastated by the loss of Justine,' he added, as he was comforted by his son Zach during the press conference.

Don's voice broke, and the grieving fiance appeared on the edge of tears, as he described the little he did know about what took place the night Justine died.

Family and friends have been devastated by the loss of Justine Damond (pictured)

'It was Justine that called 911 on Saturday evening reporting what she believed was a sexual assault occurring nearby.

'Sadly, my family and I have been provided with almost no additional information from law enforcement regarding what happened after police arrived.

'We have lost the dearest of people and we are desperate for information.'

Damond grew up in the northern beaches of Sydney, with her father and mother running a branch of the Dymocks bookstore chain in the local shopping mall.

A bright and bubbly young woman, she completed high school at Northern Beaches Secondary College in Manly, before going on to study at the University of Sydney.

In 2002, she graduated with a bachelor degree in veterinary science, but her passion for life and neuroscience saw her eventually pursue a career in healing.

Training to become a therapist, she went on to start up her 'meditate, evolve, create' business, through which she ran workshops, clinics and provided online advice.

But her life changed upon meeting American businessman Don Damond, with the pair entering a relationship that resulted in her moving to be with him in the U.S.

Don described Justine as 'kind and so darn funny'.

'She touched so many people. She was a teacher to so many, in living a life of openness, kindness and love,' he said. 'She made us all laugh with her great wit and her humor.'

'Our lives are forever changed as a result of knowing her. It's difficult to fathom how to go forward without her in my life.'

Justine Damond (pictured with her husband to be) was shot dead in her pyjamas by police in the United States, after calling 911 to report a disturbance in an alley near her home at South Minneapolis, Minnesota

Don's voice broke, and the grieving fiance appeared on the edge of tears, as he described the little he did know about what took place the night Justine died

Don, who promised to provide further statements as more information came to light, also thanked friends, family and strangers for 'the amazing outpouring of love and support that we received' after the loss of Justine.

'The death of Justine is a loss to everyone who knew her.'

On her therapy website , Justine described seeing many of her family members suffer with cancer as being an influence on her taking up a career in 'healing and transforming' lives.

She regularly appeared at the Lake Harriet Spiritual Centre teaching meditation and yoga classes, with many of her sessions posted to the the LSHC YouTube page.

But a friend of Ms Damond revealed that in addition to her professional help, she also selflessly assisted her friends.

Jay Peterson said that when a close friend of Ms Damond struggled to fall pregnant, she donated some of her own eggs to help, Fox 9 reports.

'That's just the kind of person Justine was,' Mrs Peterson said.

Community leader: Officer Noor (center) met with Minneapolis Mayor Betsy Hodges (not pictured) in 2016 where she praised him for joining the police force

Meeting and greeting: Mayor Hodges posted this picture of Officer Noor in his uniform to her Facebook page in 2016 along with a tribute to him

Supporters used chalk to share colourful messages of love near the alleyway where Ms Damond was killed on Saturday night

The messages were accompanied by the names of others who had been shot my police

Noor, who joined the Minneapolis Police in March 2015, has reportedly had three complaints made against him in two years - including a lawsuit.

Two are from 2017 and one from 2016 is closed and according to Lou Raguse of Kare 11 is marked 'not to be made public'.

The lawsuit stems from a police call on May 25, 2017, when Noor and two other officers took a woman to hospital and she claimed that they carried out false imprisonment, assault and battery.

According to the ongoing lawsuit, the woman claimed that Noor 'grabbed her right wrist and upper arm' when moving her, leaving her 'immobilized'.

The woman, a retired social worker from Minneapolis, alleged that she had called 911 to 'report an unknown young male who was sitting on her retaining wall behind her house smoking marijuana.'

Officers followed up on her complaint but returned to her home at 8pm to carry out a welfare check after 'one or more relatives' allegedly complained to police that she had 'some sort of mental health problem'.

WHY DID POLICE HAVE THEIR BODY CAMERAS TURNED OFF? - The use of body cameras, or portable video recorders (PVR), was initiated in Minneapolis during 2016. - Police introduced the technology in an effort to reduce complaints about the behavior of officers and also to ensure vital video evidence was captured. - In Minneapolis, where Ms Ruszczyk died, the cameras must be manually switched on by police. They are automatic in other parts of the US. - According to Minneapolis government's policy, the body cameras must be turned on when they anticipate they may be involved in a certain situation. - Situations where they must be switched on include: Traffic stops, arrests, physical confrontations, crimes in progress and suspicious person stops. - It was last week revealed that the usage of body cameras among officers in Minneapolis was low as 4% in some areas when responding to 911 calls. Source: Minneapolis Government Advertisement

The woman alleged that she told the officers to leave but they forced a way into her home through a screen door and told her she was going to hospital for a 'mental health crisis.'

'Defendant Officer Noor grabbed Plaintiff's phone from her hand and then grabbed her right wrist and upper arm, thereby immobilizing her,' the complaint alleged.

She was eventually released from hospital one and a half hours later after a physician ordered that she was discharged, according to the court documents.

Noor, 31, has in the past been personally praised by Minneapolis Mayor Betsy Hodges.

He also holds a degree in administration and economics.

Minneapolis Chief of Police Janeé Harteau issued a statement on Monday calling the death tragic.

'I have many of the same questions and it is why we immediately asked for an external and independent investigation into the officer-involved shooting death,' said Harteau.

'I also want to assure you that I understand why so many people have so many questions at this point. I've asked for the investigation to be expedited to provide transparency and to answer as many questions as quickly as we can.'

Many of Justine's family, friends and loved ones were emotional at the press conference

On Monday morning the heartbroken stepson of Damond appeared outside his home and had harsh words for Officer Noor.

'Why? Why did you do it?,' said Zach Damond.

'He has no idea the impact that he had on thousands of people. No idea.'

'I hope that he wakes up every single day and thinks about it, and then I hope that he thinks about how he can be a better person because that's what she did every single day. And if you don't do that, then you're not even living, either, man.'

Ms Damond had a strong stance against guns, and there was no way she would have been armed on Saturday night, her friend Hannah, 21, told the paper.

She also explained Damond, who had already taken her fiance's last name, often spoke about the benefits of Australia's tight gun control.

Despite her misgivings, Damond had elected to give up her life in Sydney for one in Minneapolis, where she lived with her fiance Don, who she described as the 'amazing, handsome hilarious, rockstar love of my life'.

Damond was due to marry fiance Don Damond, a former musician, in August, and become a step-mother to his 22-year-old son Zach.

At the time of the shooting Mr Damond, the vice president of Little Six Casino, was away on business.

Her soon-to-be stepson Zach was reportedly also not at the home on Saturday night, returning on Sunday to discover the crime scene.

And just hours after the shooting he spoke to a local activist group, slamming police over the death of Ms Damond - who he called his 'best friend'.

'Basically my mum's dead because a police officer shot her for reasons I don't know,' Zach Damond said.

'I demand answers. If anybody can help, just call police and demand answers. I'm so done with all this violence. It's so much bulls**t. America sucks.

'She was a very passionate woman, she thought something bad was happening - and next thing you know they take my best friend's life.'

Her friend Matt Omo told Astralia's ABC he hoped something positive could come from the tragedy.

'I only hope this evolves into something that can make a positive impact for the world,' he said.

Family friend Julia Reed addressed media on Monday, and said the woman would be 'undoubtedly' very missed.

Ms Damond, also known as Justine Ruszczyk, was originally from Sydney but had been living in the US for three years and was engaged to marry American businessman Don Damond (right), 50, in August

'She was treasured and loved - we will miss her dreadfully,' she said.

Ms Reed, who had known Damond for 32 years, said she would miss: '[Justine's] energy, intelligence, and the joy she brought to my life'.

Friend Marcus Ritchie mourned 'one of the world's most caring and sensitive souls', and called her 'a true inspiration to us all' in a Facebook post.

'There is no way to justify this incident as Justine Ruszczyk was such a beautiful person,' he wrote.

'There will be a lot to answer for!'

Hundreds gathered outside the Damond home in the hours after her death to hold a vigil for the woman, with her neighbours remembering a 'beautiful light'.

Heartbroken: Zach Damond spoke to reporters outside his home on Monday morning and said he hopes the police officer who shot Justine Damond dead on Saturday night suffers

'This woman was a beautiful light, she was a healer, she was loved, she should be alive - she should still be here,' one friend said.

Pictures showed a large group of people holding hands in a drive way, with colourful chalk drawings on the pavement - including a heart with 'Justine' written inside, and a red and a yellow rose laid on either side.

Her stepson Zach shared images from the event in his Instagram story, writing: 'people really showed love, thank you'.

One image showed a sign which read: 'Why did you shoot and kill our neighbour and friend?'.

The placard was surrounded by flowers, candles and a letter.

Nearby, a tea towel with an image of Australia was hung on a brick wall.