It took firefighters about an hour and a-half to fully extinguish Saturday morning’s blaze at the former CCS Disability Action Otago premises, in Great King St.
The blaze was well-involved and upgraded to a second alarm, meaning further resources were requested, a Fire and Emergency New Zealand spokesperson said.
Four crews in total attended.
A police spokeswoman said they were making inquiries.
A scene examination was conducted alongside fire investigators.
"At this stage, police are treating the fire as suspicious."
The property was home for about 40 years to the local branch of CCS Disability Action, a national organisation that provides support services and advocacy for disabled people.
It went on sale in early 2020 as the organisation prepared to move into leased and refurbished rooms in Portsmouth Dr.
Four fire appliances were sent to the property earlier this month to extinguish a blaze that temporarily closed State Highway 1 through the city.
And in October last year, 36-year-old Aneli Helu Katea was found dead at the address.
A 25-year-old man, who has name suppression, is due to go on trial for his murder next year.
