Cyclist may have filmed moment police officer shot dead Aussie bride-to-be

A mystery cyclist filmed part of the fatal encounter where a US police officer shot and killed Australian bride-to-be Justine Ruszczyk Damond after she called 911.

Officer Mohamed Noor was reportedly sitting in the passenger seat of a police car when he leaned over and allegedly shot across his partner, Matthew Harrity, killing the former Sydney resident last Saturday night.

The unreleased footage now offers a potential breakthrough in an otherwise stagnant investigation.

Authorities announced on Friday they had identified and interviewed a male cyclist who was spotted at the scene.

Days earlier they had asked for the mystery man to come forward.

Officer Mohamed Noor was allegedly sitting in the passenger seat of a police car when he leaned over and shot across his partner. Source: Minneapolis Police Department

Justine Ruszczyk Damond was shot dead by police outside her Minneapolis home. Source: AAP

The Minneapolis Star Tribune reported on Saturday a source with direct knowledge of the investigation said the witness filmed part of the encounter.

What he filmed was not released.

Ms Damond, 40, formerly of Sydney's northern beaches, called police about 11.30pm last Saturday after hearing a woman's screams and fearing a sexual assault was taking place.

What happens next will be the subject of a major investigation.

Ms Ruszczyk Damond was engaged to marry her 50-year-old partner Don Damond in August.

Don Damond said he had been left in the dark as to why authorities shot and killed the woman he was supposed to marry. Source: Twitter

Despite mounting protests, Officer Noor has remained silent as to why he shot across his partner and struck Ms Damond in the stomach.

Minneapolis Police Chief Janee Harteau announced her shock resignation on Friday, writing “last Saturday’s tragedy, as well as some other recent incidents, have caused me to engage in deep reflection”.

Enraged and grieving local residents are now demanding Mayor Betsy Hodges follow suit.