READ MORE:
• Beaten 4-year-old: Oranga Tamariki says the agency had worked with the family previously
• Flaxmere 4-year-old: Oranga Tamariki had 'prime role' in events leading to beating - kaumātua
• Injured Flaxmere 4-year-old: Uncles claim boy wasn't assaulted
• PM Jacinda Ardern's message to beaten 4-year-old's silent family members: 'Come forward'
Foster previously compared the boy's injuries, which were possibly sustained over a prolonged period, to those suffered by James Whakaruru, who was murdered by his stepfather.
He stated they were the worst he had seen in his 30-year career with police.
He said on Monday the boy was now talking.
"He's conscious and he responds to a few things from what I understand," Foster said.
However, the entire case was not simply a matter of asking the boy who assaulted him, and then arresting them.
"It's a complex case. We'll make decisions on arrests once we have all the material in front of us and also once we have consulted with the Crown."
The boy was taken to hospital after a relative called police on January 29.
Members of the boy's extended family, as well as his stepmother and father, were at his Ramsey Cres home during the time period when it is believed he was beaten.
At the start of the investigation, Foster expressed frustration that some members of the family were not telling authorities everything they knew.
Foster told Hawke's Bay Today that while police had engaged with the boy's stepmum and father, who have yet to speak to media, he couldn't say anything else.
"We've been engaging with them all the way through, that's all I can say."
The boy's family had previously been involved with Oranga Tamariki in what they said were "challenging circumstances".
Alison McDonald, Oranga Tamariki deputy chief executive Children & Families South, told Hawke's Bay Today the agency was restricted in what it could say about any update relating to the boy.
"To protect the young boy's privacy, we are limited in what we can say," she said.
"There is also an ongoing police investigation, and matters before the Family Court. We can confirm we are still working alongside health professionals to support the boy's rehabilitation.
"Oranga Tamariki is continuing to work with his family."