But they do not want to make any judgment about what happened to their granddaughter until they see their daughter.
"Accidents can happen to anyone. We love her, that's why we want to get there. Now my granddaughter's gone and my daughter needs help - she needs love," Mr Leaso told the Herald.
"Those kind of things can happen to anyone, but in the meantime we're really concerned about my daughter."
Mr Leaso and his wife will travel to Cairns on Monday to bury Faith and support their 27-year-old daughter.
Leaso has two other daughters younger than Faith, Gloria and Harmony, and is due to give birth next month.
Australian police prosecutor Senior Constable Bob Soper told the Cairns Magistrates Court on Wednesday that once forensic and pathology tests were carried out it was possible that Leaso could be charged with murder, the Australian reported.
"The defendant has made admissions that she caused the death of the child by assaulting her over a long period," Mr Soper said.
Leaso allegedly "repeatedly assaulted" Faith with a metal vacuum cleaner pipe after abusing her for a year before her death.
"The 8-year-old child [suffered] from a prolonged period of physical and emotional abuse for 12 months," Mr Soper told the court.
A midwife had told police Leaso could have been suffering from postnatal depression during the period of abuse, he said.
Leaso withdrew Faith from primary school to hide the pattern of abuse, he told the court.
"In November 2010 the defendant removed her child from school following an intervention by the Department of Child Safety, it is alleged to conceal the child's injuries by taking her out of school."
When he arrives in Cairns, Mr Leaso hopes to help his daughter "really repent and turn back to God".
"Now my granddaughter's gone but what we're concerned about is the soul of my daughter."
Paulo and Ipu Leaso adopted Ane from Samoa when she was 2 and took her back to Tauranga with their elder daughter, also called Ipu. The girls were raised and schooled there.
After Faith was born, the family moved to Australia in 2005 to pioneer a Samoan church in Cairns.
Mr Leaso's two daughters stayed there while he and his wife came back to New Zealand in 2010.
While the couple were in Cairns, they looked after Faith.
"She was a really good girl ... a very good girl," Mr Leaso said.
His elder daughter, Ipu, who also lives in Cairns, called him on Monday and told him that his granddaughter had died.
"It was a very, very big shock to us."
Leaso's young daughters are staying with her partner of two years, Matthew Webb, but Mr Leaso said he and his wife would look after them when they arrive in Cairns next week.
He hoped to bring the girls back to New Zealand with him.
Mr Leaso said Faith's father lived in New Zealand but was "not in the picture".
