Moko's mother has urged victims of domestic violence to get out and "never look back" in order to protect themselves and their children.
Nicola Dally-Paki is giving evidence at the Rotorua District Court in the inquest into the death of her son.
If her other son was not sick - or she was allowed to stay in Starship Hospital with him, or able to get housing nearby - Dally-Paki said she would not have needed Moko and his sister to stay with Tania Shailer in Taupo.
Shailer and her partner David Haerewa were jailed in June 2016 for 17 years with a minimum non-parole period of nine years after pleading guilty to manslaughter.
They appealed their sentences, saying they were too harsh. But the Court of Appeal rejected the bid and said the pair should count themselves "fortunate" they were not jailed for life.
Dally-Paki said her son was sick with an infected leg after he hurt himself falling from a tree.
She believed the complications were caused by an incorrect diagnosis at Middlemore Hospital.
Dally-Paki explained she was trying to escape a violent relationship and was struggling financially on the domestic purposes benefit, as well as travelling back and forth from Tokoroa.
While waiting for an application for a bed at Ronald McDonald House, Dally-Paki said she would sneak Moko and his sister into the ward to sleep in the hospital with their brother.
Her application was declined because of her history of family violence, gang connections and possible safety risk to others.
For similar reasons, Dally-Paki was declined to get housing at the Auckland Women's Refuge.
So Moko and his sister had to stay with Shailer and Haewera. Two months later, he was dead.
Dally-Paki trusted Shailer, whom she had known for 15 years, and who also was a qualified childhood teacher.
"It was better than a gang life," said Dally-Paki. She "absolutely" regretted making the decision to send them to Taupo with Shailer.
In sometimes emotional evidence, Dally-Paki said she had learned Shailer and a Maori Women's Refufe worker went to Child Youth and Family (now Oranga Tamariki) with concerns about Dally-Paki's parenting. This was in late July 2015, less than two weeks before Moko died.
Prior to this the Maori Women's Refuge worker had organised a programme for children who had witnessed family violence.
According to Detective Inspector Lew Warner's evidence, Moko's sister told the worker that she and Shailer had been hitting Moko.
"Aunty Tania would punch Moko but she made sure to say that the punches didn't hurt," is how Marama described her conversation with Moko's sister to police, which was recorded in a statement.
However, the social worker says her original comments to police were either "inaccurately written or understood" and no violence against Moko Rangitoheriri was ever disclosed to her.
Dally-Paki was scathing about Marama's decision making.
"[The social worker] has 12 years' experience as a trained social worker and says that not once did she pick up any signs that something was not right in one of the worst child killings in New Zealand history," said Dally-Paki.
"Oranga Tamariki also did not investigate or contact me despite being alerted to a potential issue. Apparently this is because Oranga Tamariki perceived me as the perpetrator.
"The professionals knew where to find me when my son was pronounced dead but they did not contact the Auckland DHB social workers that work at Starship to gather evidence about me and my background for that investigation.
"If they had, they would have been notified by the Auckland DHB social workers and my Moko would still be alive."
Since Moko died, Dally-Paki says her life has been "challenging to say the least" but this does in no way compares to the torture that Moko and his sister suffered.
"I accept that I as a victim of domestic violence made mistakes, my children and I live with those mistakes every day.
"I believe the policies and procedures assisted in bad decision making that led to my son's death ... I will also continue to advocate for families of domestic violence and encourage them to get help free of judgment or criticism.
"Perhaps if I had been judged less harshly, Moko would be in my arms today."
Adam Lewis, the lawyer representing the Ministry for Vulnerable Children Oranga Tamariki, asked Dally-Paki what advice she had for other victims of domestic violence.
"Make a plan, get out and never look back. Don't be ashamed to ask for help. Go to uni, get a job, go after your dreams."