Close friends of Justine Damond have made an emotional plea to the officer who killed the Australian, urging him to tell investigators why he shot her.

Tom and Carole Hyder have been comforting Ms Damond's fiance Don Damond since the Australian woman was shot by officer Mohamed Noor in an alleyway outside her Minneapolis home.

Mohamed Noor shot Justine Damond as he sat in the passenger seat of a Minneapolis police car ( AP: City of Minneapolis )

And they say his grief is being amplified by the lack of answers.

"Have a heart man. There's just families involved. Your family's involved, our family's involved, our friends are involved," Mr Hyder told 7.30.

"Yes, you have a legal right [to refuse to be interviewed], but just say what happened. There are people involved here."

'She'd just met the love of her life'

Sorry, this video has expired Justine Damond's fiance speaks after she was fatally shot by Minneapolis police

Mr Hyder described his joy at first meeting Ms Damond, and said they became friends within minutes of Mr Damond introducing them.

"She'd met the love her life and she would let you know that," Mr Hyder said.

Sorry, this video has expired Justine Damond's father calls for justice for his daughter

"Obviously [it was] a big, big choice to move over here from Australia. But whenever the two of them were together you could just feel the energy, you could feel the love. They found each other from across the planet, and with plans to be married in just a few weeks."

Mr Hyder arrived for the interview with 7.30 from comforting Mr Damond, who he has spent much of the last week with.

"He'll just say, 'I don't want to be alone,' and then he'll sit and then he'll start heaving and weeping and then just sort of pull himself back together.

"Another man who'd been shot by police, Philando Castile's mother just came over and when the two of them embraced, oh my goodness, he just lost it all again."

A memorial to Justine Damond at the site of where she was killed. ( ABC News: Conor Duffy )

'This just doesn't seem fair'

Carole Hyder said Mr Noor's refusal to speak to investigators was "making it a lot harder".

"It seems like Don deserves an answer, whatever it might be, whatever the answer," Ms Hyder said.

"But to protect the person who did this just doesn't seem fair. When you look at it, the alley was lit — it isn't like she was lurking in a dark shadow and she popped out at them.

"From what Don said, she wears these kind of cotton pyjamas, it's like, well, they couldn't miss her or mistake her for an ambush."

A memorial is being planned for Ms Damond and is expected to take place in Minneapolis early next month.

Embattled Minneapolis Police Chief Janee Harteau resigned over the weekend after being criticised for not returning from a holiday to deal with the crisis.