Partner of Constable Mia Lay pays tribute after fatal Sydney police car crash

The partner of Constable Mia Lay says he has lost the love of his life a day after she was killed in a police car crash.

Daniel Vasquez, who is also a member of the NSW Police Force, was among the family and friends who placed flowers at the location in Redfern where the 20-year-old died.

Her father planted bright yellow flowers at the site.

"She was the happiest girl I've met when she was with me, when she was at work," Mr Vasquez said on behalf of the family.

"And I've asked for everyone to remember how stunning and beautiful she was.

Just 16 months into her policing career, Constable Lay was responding to reports of a stolen car in the nearby suburb of Glebe.

She was sitting in the passenger seat of a marked police vehicle travelling along Gibbons Street, when it hit a tree near the intersection of Regent Street in the early hours of Friday morning.

She died at the scene. The 24-year-old driver suffered facial injuries, and was taken to Royal Prince Alfred Hospital, but has since been discharged.

Mr Vasquez said that Constable Lay's mother, Tamara, wanted everyone to know how much her daughter had loved her work.

"She was happy in the police, she was good at her job and how loved she was by everyone in the community.

"She was a kind-hearted person and gave so much love to everyone that she cared about."

'Thank you for your courage'

It was a sentiment shared by Redfern resident Tim Cochran.

He recalls thinking, after Constable Lay responded to an incident earlier this year, that she was the kind of person "that brings a lot of good into the world", and says her untimely death has "hit him pretty hard".

In January, Mr Cochran called Triple Zero when he found a man unresponsive in a park.

She took control when she arrived, he said, as he "watched her do her thing", leaving him in awe.

"She got the guy moving and responding," he said.

"She just struck me as an incredibly confident and competent, and reassuring person for someone her age.

"I just remember thinking to myself 'This young woman, half my age and is pulling this off' … It felt good, she made me feel better, and I wasn't the one in need."

While he did not know her, he added, she came across as someone who was "clearly doing the thing that she was meant to do".

On Friday, NSW Police Commissioner Mal Lanyon said she had shown "exceptional promise" in the short time she had been in the Force.

"To Mia 'Thank you for your courage, thank you for choosing to join the NSW Police Force, and thank you for serving the community of New South Wales, you will not be forgotten'," he said.

The investigation into the critical incident is ongoing and is being assisted by the Crash Investigations Unit.

"It will be a complex investigation, but we will get answers out of that, we have assured the family members of that," Commissioner Lanyon said.