Prosecutors are trying to bolster the murder charge against the former Minneapolis police officer accused of using “tragic accuracy” to shoot dead Australian life coach Justine Damond Ruszczyk.

Mohamed Noor initially was charged with third degree murder and manslaughter in the second degree, but prosecutors have asked a judge in Minneapolis to add a more serious second degree murder count.

Ms Damond Ruszczyk, 40, formerly of Sydney, was shot dead as she approached Mr Noor’s police vehicle in an alley behind her Minneapolis home just before midnight on July 15 last year.

“There is probable cause to believe the defendant committed second degree intentional murder and the State respectfully requests that the court grant the State’s motion to amend the complaint,” prosecutors wrote in Thursday’s filing.

Ex-police officer Mohamed Noor has refused to speak with investigators. Photo: AAP

Ms Damond Ruszczyk had called police after hearing a woman’s screams near the alley.

Prosecutors alleged Mr Noor “knew exactly what he was doing and that he intended to do it” when he shot from the passenger seat of his police vehicle, across his partner in the driver’s seat and out the car window hitting Ms Damond Ruszczyk in the stomach.

“That is probable cause for second-degree murder,” prosecutors wrote.

“The circumstances surrounding the crime show that the defendant acted with the intent to kill.

“He fired at Ms [Damond] Ruszczyk from no more than six feet (1.8 metres) away.

“He fired with tragic accuracy, managing to send a 9-millimetre bullet across his partner’s body and through the narrow space of the open driver’s side window.

“His bullet struck Ms [Damond] Ruszczyk in her torso, five inches above her waistline, and caused nearly immediate death.

“As a trained police officer, the defendant was fully aware that such a shot would kill Ms [Damond] Ruszczyk, a result he clearly intended.”

Mr Noor, no longer a police officer, is scheduled to face a jury on April 1 in Minneapolis.

Mr Noor is already charged with third-degree murder and manslaughter, and has declined to speak with investigators.

Mr Noor’s lawyers had argued he acted reasonably because he feared he was in danger.

Ms Damond Ruszczyk’s father, John Ruszczyk, has filed a $US50 million ($68 million) civil rights lawsuit against Mr Noor, the city and others.

-AAP