The father of four young children killed with their mum in a possible murder-suicide car crash believes authorities could have prevented their deaths.
Charmaine Harris McLeod, 35, Aaleyn, 6, Matilda, 5, Wyatt, 4 and Zaidok, 2, died in a head-on collision with a truck near Kingaroy on May 27.
Homicide detectives are investigating the deaths as a possible murder-suicide.
There are reports a note was thrown from the car shortly before the crash.
The children's father, James McLeod, has told The Courier-Mail on Wednesday that authorities turned a blind-eye to his warnings that she could hurt their children.
"She's just been a lying, vindictive, evil, nasty person," he told The Courier-Mail.
He said he had separated from his ex partner to protect their children.
"I've always known that she would do something like this to the kids. I've let judges know, I've let lawyers know, I've let DOCS (the Department of Child Safety) know, I've let police know.
"They've all turned a blind eye. This all could have been prevented if they did something. (I've been telling them) for years."
Comment was being sought from DOCS. Police would not comment on the ongoing investigation.
Queensland police have said it could be months before the cause of the firey car crash on a rural road is known.
Ms McLeod also reportedly posted on social media late last year that she had been struggling with mental health issues, and had been dealing with Department of Child Safety, Youth and Women.
