Information could also be provided anonymously via Crime Stoppers on 0800 555 111.
At the peak of the blaze, eight fire trucks were on the scene.
The fire gutted the Avondale church. Photo / Andrew Matthew.
On Monday, Detective Senior Sergeant Rebecca Kirk, of Auckland City Crime Squad, said investigations were in the “very early stages”.
Auckland Catholic Diocese general manager James van Schie, also at the church in the hours after the fire, said the parish was established in 1921 and the church built in the late 1950s.
“For over 100 years, it’s been a vital part of the fabric of the Avondale community,” he said.
“There are so many Aucklanders who trace their family history here; baptisms, funerals, weddings. It is a vibrant parish.”
Firefighters at the scene of the blaze at St Mary’s Catholic Church on Great North Rd in Avondale. Photo / Hayden Woodward