A man has appeared in court on Friday, charged with throwing a molotov cocktail at a property in Stokes Valley.
The 21-year-old appeared in Hutt Valley District Court facing a count of damaging the property with an explosive.
The police say it relates to a fire at the block of flats on 10 October.
He has been remanded in custody without plea until a bail hearing on 5 December. He cannot be named for now.
Meanwhile, there were two other fires at the same property in recent weeks. One on Tuesday left an elderly man seriously injured.
Police were continuing to investigate all three fires, detective inspector Haley Ryan said.
"We believe there is a strong possibility that other people are involved with that fire on Thursday 10 October, which is why it's so important that we get as much information from the public as possible to help us build a picture of what occurred on that occasion, and the other two occasions."
Police have also established a silver or grey car was seen driving in the vicinity of Hanson Grove just prior to the latest fire.
"We need to hear from anyone who may have CCTV footage of this car, or anyone who may have seen it. We know it has been speeding around the Stokes Valley area when the fire started.
"We also still want to hear from anyone with information about a male seen riding a bike barefoot around that time."
It was possible neither the cyclist nor the occupants of the vehicle were involved in the fire, Ryan said, but they may have crucial evidence that could help.
"At the heart of this is a respected 82-year-old man who is critically injured as a result of this act."
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