A 17-year-old boy was previously charged with causing grievous bodily harm and breaching bail. Before she died, Miller’s partner Phillip Edmonds told reporters he was “struggling”.
“I’m so shocked from the accident, from my partner’s accident,” Edmonds said.
“I was there trying to protect my family.
“I’m struggling at the moment and I just want to let everyone know to be there for Dianne, my baby and me.”
Miller, who was five months pregnant, went into cardiac arrest after a piece of concrete was thrown through her car window and struck her head while she was with her young family doing some evening grocery shopping in Perth on Tuesday.
“All I heard is there was an argument, and my sister told them to go away, and as they drove off, someone threw a brick through the window,” Clifton said.
“She didn’t even see it coming. It hit her straight in the temple.
“We are destroyed, we want these people whoever they are, brought to justice.”
Clifton said his sister would not have wanted violence to erupt in reaction to her death and called for calm.
“She’d like everyone to get along. No violence is the best for everyone,” he said.
Decribing her, Clifton said she was “one of a kind; kind to everybody; good-hearted; good morals; well-respected”.
He previously said his younger sister had always acted like she was the oldest and supported everyone in the family.
“She is our rock but now I’ve got to be everyone else’s rock,” he said.
“She’s the most beautiful person you’ll ever meet.”
Western Australia Premier Mark McGowan said that the situation was “very, very tragic”.
“I think her family are obviously going through a very difficult period. It’s very, very sad for her and her unborn child,” he told reporters.
“It’s one of those things that is beyond description that this could happen to someone.
“It’s a very sad event that you wouldn’t wish on anyone.”
Miller was due to find out the gender of her second child next week.
Police said there was a fight at the Waterford Plaza carpark on Manning Rd in Karawara between 7pm and 7.30pm on Tuesday.
“It will be alleged during the altercation, the 17-year-old male threw a rock at the vehicle, which went through the open front passenger-side window, hitting a 30-year-old pregnant woman in the head and causing her to go into cardiac arrest,” police said in a statement.
Police officers and members of the public performed CPR on Miller until paramedics arrived.
The boy, from Kensington, has initially been charged with causing grievous bodily harm and breaching bail. He faced Perth Children’s Court on Wednesday and will face a bail hearing next week. Inspector Brett Baddock said the parties were not known to each other.
“I put it down to quite simply (allegedly) senseless, unprovoked violence, which is unacceptable, and we won’t tolerate it,” he told reporters.
Police said their investigation was ongoing.